• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Temp fluctuating

K

Kabledog

New member
Temp gauge goes high/low then stays close to red. I changed temp sensor, fixed melted wires on pigtail, and finally attached my ODB B/t and checked the temp to verify temp from gauge was correct. Car reached 245/250. Just flushed cooling system, installed new radiator, and the car was very thirsty shortly after ODB test. White sweet smelling smoke from exhaust, and coolant reservoir smells of exhaust/hint of fuel. Car originally had water in oil, so I changed the manifold gasket, my gut insticnt told me to just do the head gasket also but being by brother in laws car, he made the call. Was I right in thinking the head gasket?

Thanks in advance

Kabledog.
 


how long did you let it run after the lim job? could just be cold exhaust pipes.

is it still loosing coolant?

rad cap off, rev the engine, do bubbles form and pop inside the rad?

did you over heat it at some point? head gaskets are pretty tough on a 3800, unless you really over heated the piss out of it.

a compression test would tell a story if its ahead gasket gone bad.
 
Road tested after the lim and radiator job (10 quarts 50/50 antifreeze/distilled water), After the second test I needed to add coolant, she sucked the reservoir dry on start up. Did a compression test on the back cylinder (1), and the front cylinder (2) before my flex line stripped out. The reading on both was 60-65 psi, book suggest minimum 100, wasnt able to get a reading on others due to faulty equipment....(go figure).
 
After obtaining another compression tool, I was able to test all cylinders and all came back the same, 60-65 psi.
 


So any ideas before pulling the heads? Like I said new thermostat, new sensor, new pig tail, ODB reads same temp and fluctuates with dash gauge. I have had to add water since filling the radiator after replacing (2 gallons), bled the system till the bleeder looked like it was pissing, coolant has escaped from a new radiator cap twice during this (seems like a lot of pressure), overflow tank has a little excitement going on also, all cylinders reading 40 psi off minimum spec. Heat gun at thermostat housing reads 208, lower hose at engine reads 180....ODB and gauge read 250-253.
 
Last edited:
J57ltr said:
All your at 160-165 psi on the compression check?

Jeff
Click to expand...
All my cylinders are at 60-65 psi. I verified my compression tool with my air compressor. Reads right at 60, 80, 100, and 120. The book suggests that if an adjacent cylinder is equally low, it would mean blown gasket, or cracked head. But what are the odds of both gaskets failing or both heads cracking and giving the same LOW reading of 65 psi for all cylinders?
 


damn i failed to notice we're in the 3100 section. head gaskets and intake gaskets fail all the time on those engines.

just maybe time to break it down and re gasket the top end.
 
I've never seen a 6 cylinder engine, or any engine really with compression that low unless all the rings were shot or the valves are totally pitted and not sealing at all

are you holding the throttle wide open and removing all the plugs and cranking until the gauge doesn't move any higher?
 


I took the plunge and decided to check the head gaskets. While they have seen better days, they weren't the culprit. As I was removing the heads, most of the bolts were a bear to wrestle with. 3 of them seemed to have missed the torquing process. They were as loose as a father loosening a bolt for his 10 year old son to remove. I was talking with my brother yesterday about the strange psi readings on the cylinders, he suggested the gauges ARE messed up because the last time he used them on a Kia Rio he received the exact same readings. I believe the untorqued head bolts was the issue, Ill know Monday when the gasket kit arrives. Thanks to all for allowing me to recieve and bounce ideas off of. If i may be wrong about the bolts, please throw me a bone with this overheating issue.
 
J57ltr said:
I've never seen a 6 cylinder engine, or any engine really with compression that low unless all the rings were shot or the valves are totally pitted and not sealing at all

are you holding the throttle wide open and removing all the plugs and cranking until the gauge doesn't move any higher?
Click to expand...

I had a TSI once where it ran on 60 psi on all 4 cylinders. My issue was a lean out and friend compression rings. The car still ran very well and boosted very hard even being 100 psi low. LOL
 
I wouldn't doubt it would run, just to me it's an indication of a slap wore out motor. Our forklift has one low cylinder at 80 psi and runs fine, and you wouldn't even be able to tell without measuring it. It's been that way for over 10 years.

OP how did the LIM look? Good luck and keep us posted. Don't forget you have different length pushrods for intake and exhaust.

Jeff
 
J57ltr said:
I wouldn't doubt it would run, just to me it's an indication of a slap wore out motor.
Jeff
Click to expand...

Thats the thing, engine ran strong and purred even before I took on the LIM. No knocks, clicks, hesitations. After the LIM, there was no more coolant in the oil, the oil looks good. It was one of the things I checked while attempting to diagnose this head problem. When I did the LIM I also installed new manifold bolts. Nothing was pinched or offset when removing the manifold to get to the heads, RV sealant took nice also. Only thing I couldnt get right was the temp which led me to the heads.
I did find a crack in the first head I began cleaning (back one), the front one had the torque issues. Found a used tested head for 75 bucks.
My brother in-law bought this car for 450. Body, frame, tires all excellent. Tranny shifts smooth no problems there. After tranny service (filter, fluid), tune-up, the first LIM, head, and engine gasket set, he is in for a total of 700. If this is the issue (untorqued bolts, cracked head, and weak gasket) he got a pretty good deal.
Any tips on cleaning the heads, I have some stubborn spots that want to hang around a bit longer:).
 
You must log in or register to reply here.
Back
Top