: Some N* questions



bone-daddy
07-13-06, 03:38 AM
hello good people. i have been reading this site like everyday for the last few weeks, and i must say, damn fine site. anyhoo, i have a few questions. i recently bought a 94 STS, the first day i had it the waterpump cratered on me. so off to the mechanic it went. so i got a reman waterpump, new waterpump belt, oil change, air filter. ok cool. well then i went on a short trip, about a 45 minute drive. i hit the highway and got her up to about 150 (kms) and the car overheated on me, hit the exit and pulled over after about 2 miles. antifreeze was spewing out of my overflow. GREAT. ok well i let it sit for a little and then continued on my journey. it ran ok and did not over heat until i got to the city and as soon as i stopped my temps went boom and got up to about 118*c at a stoplight, luckily i didn't have far to go. so i got it parked, got some of that new prestone any make/model antifreeze, filled up my surge tank, and the car ran alright the rest of the weekend.

fast forward a few weeks later and the cars been runnign hot i'd say, like at cruising speed around anywhere from 100-107*c, then the fan kicks in and the car SOMETIMES cools down. anyways i went to town and on my way home decided i would give my self a little treat and do the ol' WOT down a freshly paved country road. so thats fun and all but then again my temp went high but again i was close to where i was going so i got home in time. now i check my antifreeze and its down a couple liters. i filled it up with a ~50/50, that was last saturday. last night i'm out in the garage having a beer with my dad and we get to talking about it and decided to have a looksee. AGAIN its down maybe about a liter and a half. WTF? so i filled it up again. also we notice one of the radiators was FULL of bugs and debris, so very little air was getting through to my engine rad(which is basically brand new, maybe has 1000k on it) so i hosed it out and got most of the bugs and stuff out, took it for a drive and it ran a hell of a lot cooler on the highway, but still heats up to 107 at idle until the fans kick in then it cools down.

ANYWAYS i suppose i could move on to my questions after telling my (cadillac) life story. I'm running the old green antifreeze in this thing, can i use dex-cool? is it better somehow other than its lifespan? and I am interested in trying out this bars leak golden seal stuff, but i'm in canada and can't find it at wal-mart, or canadian tire, but i have yet to try an auto parts store and am VERY leary of going to the dealership. i planned on getting the thermostat done on it soon and figured if the rad needs to be drained i should get it before hand so it could be added, and if it can run dex-cool and benefit from it i might go that route aswell, but like so many others i seek the approval of you dudes, since there does seem to be some very smart cookies on this forum. oh yeah and does that sound like a headgasket problem what with the fluid going missing? there is no steam from the exhuast, and it only smells of gas while running, and never and puddles under the car when left sitting.

i'm absolutely in love with this car and if it does turn out to be the headgasket i'm afraid i'd have to get rid of it and i really don't wanna have to do it. the N* is freakin awesome and man that WOT sound and feel is amazing.

davesdeville
07-13-06, 07:35 AM
Once you run green you may as well keep it green since you now must change every 2 years anyway, there would be no benefit to Dexcool now.

IMO there's a chance it's a headgasket but probably not a big chance.

Now that there's ample airflow through the radiator, it heats up to 107*C and then the fan kicks in and cool it down, right? That part is normal.

Do a quick search and find the ways to test for a bad headgasket (leakdown test, exhaust-in-coolant test,) and go from there.

JimHare
07-13-06, 07:41 AM
First off, welcome to the Forum and let's hope your ride settles down a bit.

The easiest question to answer is the Green Stuff vs Dexcool question. The answer is YES, you can use Dexcool, BUT the silicates that are in the GREEN stuff (and NOT in Dexcool) have plated the internals of the cooling system with stuff that will require you to drain and change WHICHEVER coolant you use every 2 years or so, rather than the 5 years which an unsilicated engine would allow you to do with DexCool. Not a big thing, but it is important to remember. So the botom line here is that you will not be able to take advantage of DexCool's longer life span if you use it, but you can use it ok. There have been some concerns about having the two mixed together in a system, so I'd say, if you have the Green in it now, just keep it Green and change every two years or 24K miles (what's that, about 40K kilometers?

Next, the Bars Leak golden seal powder or the tabs sold at the dealer are the same stuff, as you've learned. The supplement is recommended for the Northstar engines, but is NOT absolutely life-critical as it is in the earlier 4.x liter engines. In the Northy, it's main purpose is to seal small nuisance seepages that may occur around hose connections and porosity leaks. If you can find it, fine, it not I wouldn't loose too much sleep over it.

However, I would strongly resist ANY temptation to use any other 'radiator stop leak' stuff - it's too likely to clog an overflow or crossover tube and cause problems.

My metric conversion skills are abysmal at best but 107C sounds like about 220F, which is right about where the two electric cooling fans should kick in. Make sure they do. They will also kick in, regardless of water temp, when the AC is on.

Check the thermostat (inside the WP, if I remember) and make sure it's operating correctly, and replace if necessary with genuine GM/Delco part.

I'm not an expert on the cooling systems, I'm sure others will chime in with better suggestions, there are lots of posts and archives about proper maintenance, which I'm sure you've seen. The only way to reliably test for HG leakage is a cylinder leakdown test.

Good luck and keep us informed.

Ranger
07-13-06, 11:30 AM
Ok, 118c is 245f, a bit on the high side. Clean out the condenser coils again from the front (condenser side) and again from the rear (radiator) side with compressed air. Change the thermostat, check the belt tensioner, check the purge line to be sure it is clear and flowing and check the cap to be sure it is holding pressure. If all that checks out OK, then do a cylinder pressure test.

bone-daddy
07-14-06, 03:59 AM
thanks all for the replies. now my next question would be is there an aftermarket manual(haynes, ect.) for cadillacs, or possibly one online, or am i gonna have to fork out a handful of casholas at a dealship to get my hands on one? oh and as far as the bars leak goes i can easily get the regular old bars leak, the kinda blackish type stuff, but is that not recommended?

I have cleaning out my radiators on my weekend agenda, and also i'll be trying to bend back some fins as there is a few spots that have been blocked off, probably by someone pressure washing them, and now the fins are all bent inwards, thus blocking my precious airflowage. I can borrow a rad pressure tester kit that i can do the coolant system and the cap with, so i'm gonna try to get that done asap aswell.

i have read one here about pressurizing the coolant system for a few hours and pulling the plugs and turning over the engine and looking for rad fluid, but i was talking to the head mechanic at my shop (i work on boats) and he says that doing that is not a good idea as you basically are forcing the water into your cylinders and can seriously do some damage. now i mean i'm not a mechanic (yet) but i would tend to belive him since hes been doing boat mechanics for about 30 years, and i mean even though there are very large differences in cars vs boats, its BASICALLY the same setup, but materials used and whatnot.

Oh yeah and as far as cleaning out the rads, when you say do it from the inside, how the hell do you even fit your arm down into there??? i might have to go hire some children to do this for me.

davesdeville
07-14-06, 05:51 AM
Go to http://www.helminc.com - get a Factory Service Manual (FSM,) nothing from Haynes or Chiltons is worthwhile. Also check eBay.com.

Pressurizing the cooling system will force coolant into the cylinders IF and only if you have a bad headgasket. So that's what you want to find out, if coolant is making it past the headgasket into the cylinders.

Ranger
07-14-06, 11:11 AM
Yep, Helm manual is THE factory service manual and the only one to get. Expensive if you buy it new from Helm but worth every penny. Try Ebay first.

It's kind of hard to blow out the radiator fins from the back side but just do what you can. Not that critical. Definately straighten out those fins. I do it all the time to fix the stone dents. A small pocket knife will work great. It is tedious and time consuming, but if you have large areas from a pressure washer, that will cause major problems with air flow and overheating.

As far as pressurizing the cooling system, your friend is technically correct. If you were to leak enough coolant into the cylinder and crank then crank the engine, it is possible to hydrolock it. On the other hand, you are doing it with the plugs removed so as to see any mist being sprayed out on the compression stroke so there is a vent in the cylinder to prevent hydrolock. That said, the best way to check for a bad head gasket is to pressurize the cylinders one by one with shop air through the spark plug port with the piston at TDC compression stroke and watch for bubbles in the surge tank. I'm sure your mechanic friend will agree.

JimHare
07-14-06, 11:25 AM
oh and as far as the bars leak goes i can easily get the regular old bars leak, the kinda blackish type stuff, but is that not recommended?

THAT IS DEFINITELY NOT RECOMMENDED


Do not use anything but the Dealer 'Cooling Supplement Tabs" or the BarsLeak Golden Seal Powder (sold in tubes) from Walmart.

Ranger
07-14-06, 09:50 PM
Use Barsleaks product HDC (tabs) or G12BP (powdered tabs) ONLY. Tabs from the dealer are the same as Barsleaks HDC tabs.

davesdeville
07-16-06, 08:34 AM
Do not use anything but the Dealer 'Cooling Supplement Tabs" or the BarsLeak Golden Seal Powder (sold in tubes) from Walmart.

Or your favorite auto parts store that isn't killing the country as much... Plus you won't have three people open their doors into your car and then have to wait for half an hour in line. /rant

bone-daddy
07-16-06, 06:39 PM
well did the fins on the condenser or whatever is in fron t of the engine rad and it seems to have worked out pretty good. i used an o-ring pick and a few hours, but last night i gave her the old WOT and she went from 93*c to 107 and i got a little worried but boom the fans kicked on and it dropped right back down to about 93. so i'm happy about that. also i "modded my grille by going to home depot and buying a roll of fiberglass window meshing and cutting out a section and fitting it behind my grill to keep to bugs out, so we will see how good that works.

oh and i can't seem to find the FSM from helms, i go through the dropdown menus and it returns no results for a 94 STS.

edit - well with a little more screwing around with the options on the helms site i found the manual.

Ranger
07-16-06, 06:48 PM
That bug screen mod will block air flow and cause you to run even hotter. Get rid of it.

krimson_cardnal
07-16-06, 08:00 PM
hey ranger - i was thinking about putting fog lights in the bumber openings either side of the plate frame. think that might effect cooling?? something i've wondered about. really don't like messing with air flow.

Ranger
07-16-06, 08:06 PM
Probably not much.

krimson_cardnal
07-16-06, 09:34 PM
thanks - i'm eyeballing a pair or remote controll driving lights - 55w halogens that'll fit nicely inside the bumper opening

just need to figure out how to drill and position 'em.

bone-daddy
07-17-06, 12:57 AM
you really think that fiberglass mesh screen will block my airflow THAT much?

anyways i have an update. tonight we took out the thermostat, since we figured it might be f'd. well i boiled up some water and it only opened a tiny little bit. so yeah. so then i tried running the car sans thermostat, figuring that way at least i'll have a constant flow of coolant, thus the engine would run cooler. i mean just to try it out as i'll be getting a new therm tommorow. but it seems like now it runs even hotter. WTF? man it seems like everyday this car is getting closer and closer to going to the auction for someone else to deal with.

edit - before we took out the thermostat we tried runnign the car with the rad cap off. the car reached 102*c on the gauge and then it boiled out of the surge tank, like bigtime. so thats what led to the taking out of the thermostat. also, once the thermostat was out when i started the car i got some pretty white smoke out my exhuast for about 30 seconds....

Ranger
07-17-06, 11:37 AM
Running it without a thermostat will cause it to overheat. Don't do that.

Yes, a bug screen will cause it to run hotter. I always used one many years ago. After buying a new (used) car I put one on like I always did. I also always put a set of mechanical guages in them back then and I noticed it starting to overheat. Removed the bug screen and it went back to normal. Haven't used one since. Todays cooling systems are much smaller than the old days and hold much less coolant. Radiators are much thinner and the systems don't have much over capacity so they must run at maximum efficiency. Those screens will deflect more air than they will pass.

bone-daddy
07-17-06, 09:20 PM
well i'll be damned. thanks for the advice ranger. i took it out and it did seems to be a little cooler. but yeah i got a new thermostat today and i'm in the process of putting it in right now, but i thought i'd come on here and make sure i'm doing it right. basically whats going on is the rubber o ring around the new thermostat fits just snug into the groove in the housing, but when i wedge it into it, it just pops out. also, when i took the old one off it had a paper gasket on it. that gasket was fubar. i got another one from my mechanic but it appears that it is smaller, or at least the hole for the coolant is smaller. it would fit the housing itself perfectly but like i said, the big middle hole seems to be a little small and if i put it on before putting the thermostat in then the thermostat would basically push it in and probably wreck it. but i don't know if i can get it on after unless i stick it to the part of the housing thats attached to the rad hose, because i COULD do that. or i can scrap it and use silicone. someone have any tips for putting a new thermostat in?

bone-daddy
07-17-06, 10:35 PM
well. i put the thermostat in without the paper gasket, and it seems to be ok. but i let the car run up without the rad cap on, and it hit 107 and the fans kicked on but then it hit 108 and started to boil over everywhere. it probably boiled out i'd say about a liter of fluid. what the hell is wrong with my car?!?!?!? can no one help me?i'm gonna see when i can get a pressure tester and hopefully its soon because i'd like to know if its maybe just a problem there. but i kinda have my doubts.

JimD
07-18-06, 11:22 AM
well. i put the thermostat in without the paper gasket, and it seems to be ok. but i let the car run up without the rad cap on, and it hit 107 and the fans kicked on but then it hit 108 and started to boil over everywhere.

It boiled because the system was not pressurized!

krimson_cardnal
07-18-06, 12:29 PM
seems they might provide that little paper gasket for a reason - they can be trimmed out if need be - not clear what you actually ended up doing?

how's it run w/ cap on and collant up to level?

JimHare
07-18-06, 12:46 PM
Running it without a thermostat will cause it to overheat. Don't do that.

Yes, a bug screen will cause it to run hotter. I always used one many years ago. After buying a new (used) car I put one on like I always did. I also always put a set of mechanical guages in them back then and I noticed it starting to overheat. Removed the bug screen and it went back to normal. Haven't used one since. Todays cooling systems are much smaller than the old days and hold much less coolant. Radiators are much thinner and the systems don't have much over capacity so they must run at maximum efficiency. Those screens will deflect more air than they will pass.


I agree with Ranger - you don't realize how much something like that blocks incoming air flow. It looks ok when it's a 'screen', but if you think about the mass of material there, imagine it compressed down to no spacing between the threads of screen - it might be 1/4th to 1/3rd of the total surface area that's now blocked off.

Same thing goes with window screens on your house, of course. Notice that with screens on, the amount of light passing through is reduced as well? If it blocks light, it'll damn sure block air...

bone-daddy
07-19-06, 01:58 AM
well, it leaked from the housing so today i put the gasket in and no more leaks. but it is STILL getting crazy hot. well, i mean, not all the time but i WOT'd it tonigth and it jumped up to 118*C again, but again i was close to home so i let the car idle, fans were on high, and eventually after about 10 minutes it got down to about 112, so i got in and revved it a bit and it went to 98*C like pretty damn quick, but as soon as it did the fans turned off and boom up it wen, but then i just shut it off. also i noticed something odd. it was about 16*C outside tonight(i think around 60*f) and when the fans were sucking in air on the drivers side of the car the air was cool, but on the passenger side the air was hot. and thats when the coolant temp was still 115*ish. and also when the thermostat housing was leaking the coolant from it was barely warm. like luke warm, but my rad hoses were very hot, and the housing itself was hot too. like WTF?

oh yeah i should mention now that my AC doesn;t work too, like i charged it and the clutch kicked in but tehn i drove the car an hour later and no AC. no codes except when i charged and i cleared them hoping it would enable the ac but nope. and the fans don't come on either when auto AC is pressed.

Ranger
07-19-06, 04:38 PM
well, it leaked from the housing so today i put the gasket in and no more leaks. but it is STILL getting crazy hot. well, i mean, not all the time but i WOT'd it tonigth and it jumped up to 118*C again, but again i was close to home so i let the car idle, fans were on high, and eventually after about 10 minutes it got down to about 112, so i got in and revved it a bit and it went to 98*C like pretty damn quick, but as soon as it did the fans turned off and boom up it wen, but then i just shut it off. also i noticed something odd. it was about 16*C outside tonight(i think around 60*f) and when the fans were sucking in air on the drivers side of the car the air was cool, but on the passenger side the air was hot. and thats when the coolant temp was still 115*ish. and also when the thermostat housing was leaking the coolant from it was barely warm. like luke warm, but my rad hoses were very hot, and the housing itself was hot too. like WTF?

oh yeah i should mention now that my AC doesn;t work too, like i charged it and the clutch kicked in but tehn i drove the car an hour later and no AC. no codes except when i charged and i cleared them hoping it would enable the ac but nope. and the fans don't come on either when auto AC is pressed.
That would lead me to think there is a coolant flow problem, belt tensioner rusted, purge line plugged.

bone-daddy
07-20-06, 01:30 AM
hey guys, did i mention how much i appreciate all the help you're giving me. anyhoo, thanks a LOT. ok backt o updates. today i went to the dealership and bought an ACdelco rad cap, just asked for the one for my car, has no markings on it as to how many psi it is. and got the coolant supplement tabs. so then i drove around town, usually the temps were about 100-106*C, and got some antifreeze, and some distilled water. went home, opened up my rad drain plug, and drained that, then i took the shop vac and had it pumping air into the surge tank, and i got a bit more coolant out, but not a whole lot. like i probably got ohhhh say 6 quarts of the coolant out total. so that sucked. was i supposed to use the shop vac somewhere else other than the surge tank?

well anyways so i took off the upper rad hose and put all my tabs into it, put it back together and filled it up with my new 50/50 mix. it only took about a gallon and a half. dammit. anywasy ran it for a few mins sans rad cap, it started boiling up, put the cap on, then the temp climbed up to about 109*c. man i just don't know what to do, other than get that tensioner checked and the purge line. by the by, where is the purge line?

oh and also i tried to get the ac to work by using a paperclip to jump the sensor, no go, then i tried the fuse, it was good, then i disconnected the battery, still no AC clutch. like wwwwwwhhhhhhyyyyyyyyyyyyy!!?!?!?! i love this car but damn it seems to hate me. black leather in the heat we've been having with no AC, man that sucks.

JimD
07-20-06, 09:16 AM
....


well anyways so i took off the upper rad hose and put all my tabs into it, put it back together and filled it up with my new 50/50 mix. it only took about a gallon and a half. dammit. anywasy ran it for a few mins sans rad cap, it started boiling up, put the cap on, then the temp climbed up to about 109*c. man i just don't know what to do, other than get that tensioner checked and the purge line. by the by, where is the purge line?


Several times you have mentioned running the engine without the pressure cap. You could be stacking the deck against yourself that way. At sea level pressure (no pressure cap), your 50/50 coolant mixture would boil at slightly above 100 C. If you are located in the Calgary area, you are most likely higher than 3,400 feet above sea level and with no pressure cap, your 50/50 coolant mixture will boil at a lower temperature.

109 C (228 F) is NOT too high a temperature. That is approximately the temperature where the cooling fans will be turned on as you have seen.

The purge line is a rubber hose connected to a hollow bolt on the coolant crossover located within an inch of the top hose attach point. The purge line plumbing (this varies from year to year) makes its way through the throttle body and then to the surge tank. This line must flow coolant.

Make sure the purge plumbing is not plugged up. Fill the sytem and the surge tank and install the pressure cap! Operate the engine until you get to normal operating temperature (thermostat open). Blip the throttle to 3,500 RPM a few times. Let engine cool. Check coolant level at the surge tank only!

If the correct coolant mixture under the correct pressure cannot control the temperature, you will need to do some deeper diagnosis and testing.

Don't give up on it yet.

GreenMachine
07-20-06, 05:05 PM
yeah running the engine with the cap off really serves no purpose, it will almost always boil over that way. You should fill it all you can, then drive it for a bit, then fill somemore after its cooled down. Opening it up hot and running it open will only cause a boil over.

bone-daddy
07-20-06, 10:37 PM
well new update. i pulled off the line on the surge tank that goes to the intake, it was clear, blew a little air through it, collant came out the surge tank side. ok. then i went to the other side and pulled off what i belive is the purge line. pulled it off the block side and no coolant came out when hose was pulled. started the car for justa half sec to make sure coolant was getting there, it was. then i pulled the hose completely off. it was also open, but the line it connected to that goes back into the block was visibly corroded with rust at l;east at the tip. blew air into it and nothing, then blew a little more and then it came out the opening right above the upper hose, so it might have had a blockage, but i didn't actually see anything come out, blew air through the other side, got collant flowage through the corroded side. also i checked out the waterpump belt tensioner, i could move it, and it didn't look bad, but meh. and yeah thats about it.

edit - the car is now at its second home, the mechanics, getting the waterpump belt tensioner possibly replaced, and hopefully the AC fixed/running.

fanofsims2
07-21-06, 01:08 AM
In your description of the overheating problems you stated

"oh yeah and does that sound like a headgasket problem what with the fluid going missing? there is no steam from the exhuast, and it only smells of gas while running, and never and puddles under the car when left sitting"

Notice your statement about smelling gas. You should not smell fuel ever. The fuel system is a self contained system. You have on several occasions mentioned the fact that WOT it will begin to run hotter. If your injectors or orings under intake is leaking fuel and the ignition can't burn it all it can cause your N* to run hot!

Have your mechanic check it out. It can't hurt to look! :rolleyes:

bone-daddy
07-21-06, 03:27 AM
i meant the exhuast smells of burnt gas. are you telling me that i shouldn't be smelling GAS from my EXHAUST? is it supposed to smell like flowers or something, jeez man gimme a break.

Ranger
07-21-06, 04:03 PM
Exhaust smell and gas (raw gas) smells are totaly different. I think that is what fanofsims2 was refering to. In rereading the quote, I can't blame him for making that assumption.

bone-daddy
07-21-06, 11:20 PM
yeah sorry i was in a pretty foul mood last night. anyways appaerntly there was a fuse in the maxi-fuse block under the plastic shrouding above the wiper fluid resivoir that was blown that was for the electric fans that was NFG. it looks like it had battery acid spilled on it, as it was totally corroded and missing half of it and fell apart when removed. got my relays for fans check and fuse replace, mechanic ran the car for an hour and said it didn't overheat but just fluctuated between about 100-107 at idle, so thats good. and as far as my AC was concered, he said he vacuumed it and itlost all pressure after he removed it, so a big leak somewhere. argh. so i dunno, i'mma try some AC repair stuff, and see if that maybe helps, as i really am afraid to take it to an AC shop and have to find out something is wrong with it that is gonna cost me a bundle o cash. oh yeah and i guess the tensioner for the waterpump was good.

Ranger
07-22-06, 11:31 AM
DO NOT use refrigerant with a "sealer" in it to try to repair an A/C leak. You will create more problems than you will cure. Remember, repairs in a bottle (or can) don't work.

bone-daddy
07-22-06, 03:59 PM
i don't mean to get offensive, but i'd just like to know why? what other problems could percievably happen by adding this stuff? and the place that sells the repair stuff also sells an AC treatment can that apparently conditions o rings and the like, would that also be a no-no?

Ranger
07-22-06, 05:18 PM
I have been told that those sealers will ruin the compressor. I doubt that the "O" rings need to be conditioned. If you want any more info, you might go over to caddyinfo and ask KHE (Kevin). He is the A/C expert there and he always advises against any of that stuff.

bone-daddy
07-23-06, 09:05 PM
thanks ranger you've been helpful as per usual. :)

depaolo
07-26-06, 11:34 AM
In regards to your major loss of refrigrant. Check your A/C line (high side) going to your compressor. Down on the left side of the raditaor the line runs very close to a metal block that is part of your ABS. Check for the pipe rubbing that block or the hose clamp. More than one line has been ruined from rubbing on that block. Good luck Depaolo

bone-daddy
08-16-06, 04:13 AM
sorry to drag up an old thread but i just noticed something i thought was a bit odd. last night i went to town to see a movie, its about a 20 minute drive, about half of it is highway, so about 100kmph, the car runs at about 92 or 93*C, or just under 200*f. i get into town a have to reduce my speeds a bit, and it heats up a few degrees, blah blah.

anyways, what i noticed is this. before i left i checked my surge tank level, it was about 2 inches from the top. when i got out of the movie, like 2 hours after driving the car, i checked again, and the fluid level was actually up. you know that little separator inside the surge tank, well it was like at the very top of that, and before it was below it by about an inch. is that normal or wtf? seemed a bit more than odd to me.

STS-in-Nottingham
08-16-06, 12:42 PM
That is perfectly normal,
Engine will still be warm after 2 hours so coolant will be up.

djb25
09-06-06, 06:33 PM
Sorry to revive such an old thread, but I noticed that there was a mention that running a car without a thermostat will always cause it to overheat. I've never heard that before, and I'm not quite sure why this would be the case. Could someone illuminate this issue for me? Does it have something to do with the design of the waterpump?

- damion

Ranger
09-06-06, 08:38 PM
That is what our old Guru always said. I think it has something to do with the coolant flow routing if I recall correctly but I'm not positive.

chevelle
09-06-06, 11:12 PM
Sorry to revive such an old thread, but I noticed that there was a mention that running a car without a thermostat will always cause it to overheat. I've never heard that before, and I'm not quite sure why this would be the case. Could someone illuminate this issue for me? Does it have something to do with the design of the waterpump?

- damion


The Northstar has the thermostat on the water pump inlet. Most thermostats you are used to on other engines are on the exit side of the coolant from the engine, not the water pump inlet side like the Northstar. In addition, the Northstar has a large coolant bypass passage to allow coolant to recirculate thru the engine to minimize hot spots and maximize flow. Only a portion of the coolant flow goes to the radiator. The thermostat controls all of this besides just controlling engine temperature. If you remove the stat and drive without it the coolant flow will be totally screwed up and very little will go to the radiator. There is a spring loaded paddle on the Northstar stat that controls the bypass flow independent of the thermostat position or coolant temperture. Without the stat this paddle is missing and the bypass port is wide open. You do NOT want to run a Northstar without the stat. It will cause it to run hot and overheat.