overheating, now power, 83 coupe deville ht4100

[knepper]

hello everyone, this is post number one for me here on the cadillac forum. been lurking for a couple days, doing some research. problem is i keep reading contradicting advice. perhaps a caddy expert here can help me out.



i just recently bought a 1983 cadillac coupe deville with the ht4100. the car is clean with 85,000 miles. i paid $500 for it because it "needed an alternator/maybe waterpump" and the current owner needed money for a deposit on a new apartment.

regardless........i drove the car home (5 blocks). durring the trip it ran kinda rough, at stop signs, id have to accelerate slowly or it would stall, car had little power at all. the car started overheating, and the no charge kept popping on. the next day at my shop i decided to test the alt. popped the hood only to find that the alt wasnt even spinning. the belt for the crank to the waterpump was EXTREMELY loose. call autozone, they send down a new belt for that and one for the waterpump to the alt. change belts and go for a drive, alt is fine, but 5 blocks down the road its overheating again. mind you it did idle for 10 minutes before i left. ok so fine it needs a waterpump. no big deal ive changed a couple before.

the shop was dead this afternoon, so i decided to take a couple hours and change the water pump. WOW just got home at midnight!!!!! damn is a caddy different than my blazer! (and the water pump didnt seem in bad shape) 10 hours later the car is put back together and running strong. ran for 20 minutes no overheating!!!! pull it outside let it run as i shut the shop down. still runnin cool. idles funky because of a code 30, no biggie, lets get it to run for more than 5 blocks before i go investing into sensors. i drive the long way home, went seven or 8 blocks, pulled over popped the hood checked the overflow, all looks fine. drive 10 more blocks start going out of town pull over to check. all still looks fine. drive half mile into the country turn to start heading back, all still doing well. brakes stink, prolly from the car sittin for a year or better. other problem is that its still sluggish, takes for ever to get to 55. didnt like doin it, as i pulled back into town (2 mile trip) the coolant temp light came on only had to go 4 short blocks, as i pulled into my parking spot the stop engine temp light came on. shut'er down and it was boilin bad!!

ive been sittin here searching ever since.

here are the questions.

4100's warp easy under heat, i bought a car that was overheating, how bad did it overheat before i bought it? did someone cook it to the point of no return? am i wasting my time by trying to fix this motor? espicially considering the problems it has with acceleration? i know my cat is bad, the exhaust system looks old, i wanna put on a nice dual exhaust set up, but i dont wanna waste the money if the motor is junk.

maybe because that bad sensor (e30....idle somthing or orther) and clogged cat it runs like crap, and the overheating maybe cause of somethin clogged, it just needs a good flush---although when i was fillin the radioator i noticed that the top hose was flowin into the radiator pretty good.

im gonna check tomorrow to see if the bottom hose is colapsing durring acceleration.

do you think the burning brake smell might be brakes grabbin causing it to accel slow? and maybe thats also while its overheating while driving and not while sitting?

or should i be thinking that this motor is junk now and i should just buy a cheap small block, carburator, and *chrome dress up kit* . is there a cheap common motor that i can find locally in my small town of 30,000. that will bolt up to my tranny and work fairly easily? this car is just going to hangin around my shop with some big rims to advertise kinda. i wouldnt mind changing motors, but if this is easier and cheaper to fix, than id rather go the simple way. this car is only really ever gonna see small town drivin for the most part.

im gonna check my brakes and radiator hoses tomorrow, but do you think im beating a dead horse?

joe

[noahsdad]

Originally Posted by knepper

hello everyone, this is post number one for me here on the cadillac forum. been lurking for a couple days, doing some research. problem is i keep reading contradicting advice. perhaps a caddy expert here can help me out.

i just recently bought a 1983 cadillac coupe deville with the ht4100. the car is clean with 85,000 miles. i paid $500 for it because it "needed an alternator/maybe waterpump" and the current owner needed money for a deposit on a new apartment.

regardless........i drove the car home (5 blocks). durring the trip it ran kinda rough, at stop signs, id have to accelerate slowly or it would stall, car had little power at all. the car started overheating, and the no charge kept popping on. the next day at my shop i decided to test the alt. popped the hood only to find that the alt wasnt even spinning. the belt for the crank to the waterpump was EXTREMELY loose. call autozone, they send down a new belt for that and one for the waterpump to the alt. change belts and go for a drive, alt is fine, but 5 blocks down the road its overheating again. mind you it did idle for 10 minutes before i left. ok so fine it needs a waterpump. no big deal ive changed a couple before.

the shop was dead this afternoon, so i decided to take a couple hours and change the water pump. WOW just got home at midnight!!!!! damn is a caddy different than my blazer! (and the water pump didnt seem in bad shape) 10 hours later the car is put back together and running strong. ran for 20 minutes no overheating!!!! pull it outside let it run as i shut the shop down. still runnin cool. idles funky because of a code 30, no biggie, lets get it to run for more than 5 blocks before i go investing into sensors. i drive the long way home, went seven or 8 blocks, pulled over popped the hood checked the overflow, all looks fine. drive 10 more blocks start going out of town pull over to check. all still looks fine. drive half mile into the country turn to start heading back, all still doing well. brakes stink, prolly from the car sittin for a year or better. other problem is that its still sluggish, takes for ever to get to 55. didnt like doin it, as i pulled back into town (2 mile trip) the coolant temp light came on only had to go 4 short blocks, as i pulled into my parking spot the stop engine temp light came on. shut'er down and it was boilin bad!!

ive been sittin here searching ever since.

here are the questions.

4100's warp easy under heat, i bought a car that was overheating, how bad did it overheat before i bought it? did someone cook it to the point of no return? am i wasting my time by trying to fix this motor? espicially considering the problems it has with acceleration? i know my cat is bad, the exhaust system looks old, i wanna put on a nice dual exhaust set up, but i dont wanna waste the money if the motor is junk.

maybe because that bad sensor (e30....idle somthing or orther) and clogged cat it runs like crap, and the overheating maybe cause of somethin clogged, it just needs a good flush---although when i was fillin the radioator i noticed that the top hose was flowin into the radiator pretty good.

im gonna check tomorrow to see if the bottom hose is colapsing durring acceleration.

do you think the burning brake smell might be brakes grabbin causing it to accel slow? and maybe thats also while its overheating while driving and not while sitting?

or should i be thinking that this motor is junk now and i should just buy a cheap small block, carburator, and *chrome dress up kit* . is there a cheap common motor that i can find locally in my small town of 30,000. that will bolt up to my tranny and work fairly easily? this car is just going to hangin around my shop with some big rims to advertise kinda. i wouldnt mind changing motors, but if this is easier and cheaper to fix, than id rather go the simple way. this car is only really ever gonna see small town drivin for the most part.

im gonna check my brakes and radiator hoses tomorrow, but do you think im beating a dead horse?

joe

There aren't any easy swaps. The 4100 is integrated into the car's electronics with two computers (ECM and BCM). Even the similar 4.5 and 4.9 engines are tough to get running properly without a lot of trial and error.

So let's work with what you got.

1) First thing to check for is coolant in the oil. If it's present, the oil will look milky and possibly lumpy on the dipstick. If yes, the head gasket(s) are likely bad.

2) When you changed the WP did you flush with distilled water, then add 50/50 coolant and the GM sealant? Very important!

3) Are the coolant fans working? Test by entering diagnostics, letting the codes display until you get a .7.0 in the Fuel Data Center. Press ECON and release. The FDC should display F.8.5. Press and hold the HIGH button. In a few seconds, both fans should run up to full speed. Press and hold LO to slow and stop the fans.

4) If the cat is plugged, that could be the answer to your lack of power issue. It could also be the source of the 'burning' smell you describe.

5) Code E30 is an idle speed control circuit (ISC) fault. Common problem and more likely a result of your other problems, not a source of them. This fault will light the SERVICE SOON warning on your dash.

[noahsdad]

Sorry, just noticed you have an '83, so the coolant fans info doesn't apply.

[knepper]

the oil looks fine, however, somone could have changed it right before i bought it to prevent me from seeing the headgasket problem. the dip stick is not all rusty and coroded, and the filler cap isnt milky lookin. but ill still look for what you have mentioned..........

any other ideas

[knepper]

this morning i topped off the radiator with water, and drove to the shop.(5-7 blocks) when i got here i let the car run, it sat in the parking lot at idle for 20 minutes, then it started overheating. after running for 30 minutes. no hoses seem to be colapsing. the oil still looks fine.

can a severly clogged cat cause the car to overheat and not want to drive?

my mechanic doesnt have to look at it tillthe first of the week. any suggestions on what i can check until then?

joe

[HUF]

Originally Posted by knepper

this morning i topped off the radiator with water, and drove to the shop.(5-7 blocks) when i got here i let the car run, it sat in the parking lot at idle for 20 minutes, then it started overheating. after running for 30 minutes. no hoses seem to be colapsing. the oil still looks fine.

can a severly clogged cat cause the car to overheat and not want to drive?

my mechanic doesnt have to look at it tillthe first of the week. any suggestions on what i can check until then?

joe

Do the fans turn on at some 220-230F?

[carnut]

This car is a rear wheel drive? correct? I had this issue with an Eldo and I found the belt that spins the smog pump to be loose, worn out. A loose smog pump belt will allow the water pump pulley to slip at road speed possibly causing overheating. You can verify this by trying to rotate the alternator backwards against normal rotation. If it rotates, then the smog pump belt is slipping. The alt. belt only wraps around the water pump pulley, the smog pump belt wraps around the crankshaft and water pump pulleys. To tighten the belt, you must gain access from under the car! Not fun! Another overlooked item is the radiator pressure cap, could be weak, not holding required pressure, test it. Make sure and add the sealing pellets mentioned on the white decal on the radiator support. VERY IMPORTANT! to continued life of this engine. Any GM parts dept. should have it. Smash the tabs while still in their package and add the powder to the radiator. Should do this yearly as well as antifreeze replacement. Regarding the idle speed code, The throttle return spring could be weak, replace it with a GM dual spring. Also verify the cruise control linkage is not misadjusted not allowing the throttle blade from returning to curb idle.

[knepper]

ok just changed the radiator cap, the car ran outside for half an hour no problem, drive it about a mile down the road, turned it around came back still no problem, left running outfront for another half hour. still doin fine. turned it off, then it started bubbling into the overflow?!?!?!?!

i have a new IAC on its way, im gonna put that on and check the timming.

any other ideas?

joe

[carnut]

Yes, There is air still in the cooling system. Removing the cap, engine cold, coolant should overflow from radiator. If not its low. I fill a cold radiator with the engine held at about 1500 rpm, once the thermostat opens and the level drops I continue to add till full. Then I screw on the cap and let the idle return. Top off recovery tank.

[The Ape Man]

Some thoughts:
Don't trust a coolant thermostat which is used or has been overheated.
Replace it if that has not been done.
The cat can be punched out to eliminate it as a problem. Replace it when everything else has been repaired.
If the radiator is HOT and the air coming out of it isn't then it could be loaded with schtuff.

[knepper]

allready changed the thermostat, allready popped the plug on the bottom of the cat. i also today changed the isc, its starting to get better and better, i think im gonna have the cooling system flushed on monday, then im going to look into checking the timming, and new plugs and stuff

joe

[peteski]

You can actually display the coolant temp (in Celsius) by entering the diagnostics and selcting the temperature readout. That way you can drive around while knowing exactly what the coolant temperature is. You won't have to wait until the idiot light comes on to tell you the engine is too hot.

You'll find the diagnostic info on http://ht4100.com

Peteski

[knepper]

the car is at the shop getting looked at. after i changed the radiator cap, it stopped overheating. i started it up today and it through the code 30 again. still runnin very sluggish. i should have some answers in the next couple days. i told my mechanic to just check it when he gets a chance. its an extra car, not a daily driver. as i get some news ill pass it along.

joe