: small coolent leak

09-25-08, 11:07 AM
hello, I got a great deal on a 2000 DeVille, But it may have some problems, 4.6 north* 113,000 have a small coolent leak on back side of block,(fire wall side) cant see up there very well becuse transmision is in the way, dose any one know if the temp.sending unit is up there on these engines, it will leave a puddle about the sise of a silver dollar after three days of being parked,and it dose not seem to leak worse when running and hot, have check all lines and hoses they seem to be fine. any help would be great!!

09-25-08, 11:45 AM
There are two heater pipes back there that run to the heater core. For some reason they tend to rust out and leak. They are a PITA to get at. You may have to lower the front cradle mounts to tilt the engine forward so as to give yourself a little room to work. It has been discussed before if you do a search.

09-25-08, 12:22 PM
As Ranger said, there are pipes back there that give trouble once in a while. The temperature sending unit is just below and right of the throttle body, in the coolant crossover, which also has several gaskets that have a tendency to leak once in a while.

Best to find and correct the problem now......and DO NOT dump some sort of sealer in the surge tank. You will regret it in spades later........

If you have a record of service on the car/cooling system, the coolant should have been changed in 2004/2005. And it's probably close to due again.....clean DEXCOOL is one secret to a Northstar's longevity.

09-25-08, 12:23 PM
I have checked them already, they are dry, I need to get under their and wipe things clean and watch were its comming from but havent yet, little histry now, dont want to make this to long but here gose, bought car from neighbor for 500.00 its a beutifull car, he was told it had a leaking cylinder sleeve,need new engin, when i got it, there was about 2 quarts of antifreez left in it. he said it would get hot, filled system and ran it in the drivway for 45 min. then turned the air on high for another 15 min then drove it for five or six miles, didnt get hot but when it was cooled down noticed the puddle it was leaving, went to dealer and got some pellets and put them in the rad.hose then drove it for 25 miles, i drove it hard to try to get it hot,it started to get hot at 20 miles,guy i work with says blown head gasket,but i did a chemical coolant test and did not show exhaust gasses in cooling system. I was hopeing that mabey it was the temp sencer threds leaking or mabey the unit it self but if it is up there it would be a PITA, I find it odd that it dose not spray out when hot and under pressure

09-25-08, 12:30 PM
The exhaust gas test kit requires a period of time/engine operation in order to sample the gas over the coolant in the surge tank. The test, done on fresh coolant, will indicate negative.

It's not a leaking cylinder sleeve.......do searches for head gaskets in here, Seville, and Deville. Lots of info. If the rest of the car is fine to mint, do the top overhaul on the engine. For your paid price and the engine overhaul price (dealer $3500 ???) you're still not upside down in the car.

(If your temp sending unit were leaking, it would be a first........)

09-25-08, 12:37 PM
Just wanted to add that i think he was adding what ever kind of antifreez that he had because while under their i could see green antifreez so as i said there was only 2 quarts left in there when i got it so i have added new althogh when i find and fix the leak i will drain and refill.

09-25-08, 02:21 PM
Keep in mind that if he put green coolant in it, then it will need 2 yr coolant changes from now on.

09-25-08, 03:01 PM
Yes, but should I still use the DEXCOOL or reguler green as it has already been contaminated with the green kind. I used an infered thermomater to watch to see when thermostat opened, it was about 175,which seamed ok but do you think it could be acting up and closing when it shuldn't or mabey not opening all the way and thats causing it to get to hot? thought I would change it but wanted to find the leak first.

09-25-08, 04:18 PM
At this point it does not matter if you use Dex or conventional green. I'd probably stick with Dex as it is silicate free and easier on the pump seals. Sounds like your stat is opening when it should. I'd test the coolant again after it has been in there a while as Sub said.

09-26-08, 10:18 AM
Hello again, wanted to ask anthother question, next to the coolant line that runs from the water pump to the surge tank there is another small line that runs next to it then turns and goes down by the front of the engin (pass. side) where is that line go to? Thank you.

09-26-08, 10:45 AM
The small line you refer to: Does that (coolant ?) line connect to a nipple at or near the top quarter of the coolant surge tank ? If so, it is the purge line, connected to the w/p or coolant crossover area and is used to constantly bleed a metered amount of coolant back into the surge tank, thus keeping the system free of air and gasses. If you remove the surge tank cap, COLD, and start the car, a steady stream of coolant should spit into the tank airspace from the purge line. (The tank should only be half full, cold) If not, the tank nipple, line, or metered orifice near the w/p is clogged, and the system cannot purge itself of air and gas bubbles.

09-26-08, 10:54 AM
I did check that and it dose flow,but there is another tube that runs alongside that one that also comes from the water pump area and turns and gose down by the drive belt (surp.)

09-26-08, 05:07 PM
The 2000 should be the same as my '03 and I don't see the hose you are talking about. The only hose I can see on the passenger side is the surge tank overflow hose. No other hose next to the purge line on the drivers side. Maybe there was a change from '00 to '03.

Mark C
09-26-08, 06:29 PM
Just went out and looked at my 00 Deville and there is a second line, the same size as the purge line, that comes off of one of the heater tubes (that bolt to the back of the engine) just up and behind the water pump cover, and it runs across the engine under the Beaty cover with the purge line and then down the front edge of the engine headed towards the alternator/ a/c compressor area when it disappears. Its raining so I didn't feel like crawling under the car to see if I could see exactly where it went. Don't tell me I've got a water cooled alternator in my Deville. Can't imagine where else it would go to.

09-26-08, 08:28 PM
Ahha, that's it. I think the 2000 did still have the water cooled alternator.

09-29-08, 09:01 AM
UPDATE, That other line is part of the circulating coolant before the themastat opens it tees off the other line that comes from the surge tank and comes back to the water pump via back side of engin, got car up on stands this weekend and wiped every thing down so i could look for fresh leak,then started car,had cover off surge tank,heater on high,i wanted to moniter (1) level of coolant in surge tank, (2) any fresh leaks,(3) lower rad hose,when it got hot and when thermastat opened. well it did not take very long and i had heat blowing in car,after ten or fifteen min. i could tell that the thermastat should be opening soon as there was steem starting to show in the surge tank,still hot air in car then i started getting gurgaling in the surge tank so i quickly put cover back on as not to loose the coolant then checked for the warm air in the car....it was gone, blowing cold air now, shut car off upper rad. hose pressured (hard) lower still cold not pressureised,thermastat was not opened yet im thinking.......so was that air bleeding out of system? after car cooled down level in surge tank was lower than it was before i started. As for my small leak it took seven hours before one drop fell and from the best that i could see it is dripping off one of the bolt heads that hold the black iron bracket that ties the engin and trany. together. it looks like the only thing up behind that would be the head gasket......but its not leaking very much yet and not worse when running or hot.. one other thing what would be a good way to clean out the inside of the rad. with out taking it out,( don't laugh now) but what would happen if i took the hoses off the engin raised them ubove top of rad. and filled with vinager and let it sit for a while then flushed it out, (not intending on puting any in the engin) i know that the guy i got this from was putting stop leak in and it probly was not the right stuff and he probly put it in the surge tank so i am trying to make sure the rad. is not pluged up. (vinager works good on coffey pots) thanks for any thoughts!!!!

09-29-08, 05:19 PM
I think your radiator flushing method should work well. When you are finished, open the drain on the bottom to completely empty the radiator.

09-30-08, 08:47 AM
Ok, great! I plan on putting in a new thermastat soon and thought I would clean the rad. at the same time.so do you think that the bubbleing in the surge tank was just air bleeding out of system or symptom of blown head gasket?I know that probly the best way to find out is to drive it but have'nt licenced or insured it yet so trying to get it straightend out in the driveway. since i got the car the coolant leak seems to be not as bad,as those tabs seem to be working do you think the only place above or behind that black iron bracket is the head gasket,or could there be a nousence leak from that area? (im not in deniel that it is the head gasket just want to be sure) talk to you later.

09-30-08, 11:25 AM
I gues what i was hopeing to find is that for some reason the cooling system got low on coolant and was getting hot and the guy before me never got the system all the way full again as his wife drove the car and i assumed she would tell him it needed coolant and he would put some in (but not enough) then she would drive it and it would boil over again so he would add more, so thats why i am trying the easy stuff first.

10-02-08, 04:03 PM
I will mark this one down as more proof that 2000+ can and DO have Headbolt failures just like all the rest.

10-02-08, 04:48 PM
They are not immuned. Just less likely.

10-17-08, 11:08 AM
Hello again, small update i regesterd the car and am now driving it, runs great love the power it has, my son wants it bad, it still is dripping a little coolant from the same place as it was, when I change the oil I want to take that black iron bracket off that gose between the block and trany so I can see up where the coolant is comming from, dose any one know if i remove this will things stay lined up so i can put it back on? I've put about 300 miles on so far and temp has never gone past the middle line, coolant level has not seemed to have droped, surge tank is about half full, How many miles would you say would be enough to put on it before I check the coolant for exhaust gases again? thanks for your help!

10-17-08, 08:50 PM
Don't mean to get off topic here, but 2000+ engines are just as prone to head gasket failure as the rest. We just have to give it a year or two before we'll start seeing more failures. The bolts still have the same M11x1.5 fine thread bolts. A bit longer, yes. The top rows of head bolts don't go in any deeper than the 93-99 engines, the bottom rows of bolts do go in a bit deeper. But the problem lies in the fine threads, and the rusting gaskets.

I've done a 2000 and a 2001. Same problems.

10-17-08, 08:55 PM
Another thing- Northstars can have cracked cylinders. I've seen a 1995 L37 4.6, cracked cylinder- through the aluminum and the steel liner. Two 4.0 Aurora engines, both with cracked cylinders, also through the liner. Had me convinced it was a leaking head gasket - what started out as a HG job, turned out to be an engine swap.

This makes 3 Northstars (yes I know 4.0's aren't technically Northstars) with cracked cylinders. Hope I don't find any more.

10-17-08, 11:35 PM
Don't mean to get off topic here, but 2000+ engines are just as prone to head gasket failure as the rest. We just have to give it a year or two before we'll start seeing more failures. The bolts still have the same M11x1.5 fine thread bolts. A bit longer, yes. The top rows of head bolts don't go in any deeper than the 93-99 engines, the bottom rows of bolts do go in a bit deeper. But the problem lies in the fine threads, and the rusting gaskets.

I've done a 2000 and a 2001. Same problems.There's 28 '00-up N* with head/bolt/gasket failure right on the poll: http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/122898-northstar-headgasket-bolt-failure-please-let-18.html