1994 Chevy Suburban overheating

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Originally Posted By: cchase
The throttle bodies themselves on these are easy to check, just pop the air filter housing off and look. The intake manifolds themselves don't get dirty on these trucks.

From everything you've said here, it seems obvious this truck has been neglected in some kind of substantial way. The problems it's having are indicative of such. Vehicles that are maintained don't just "start" spraying oil everywhere and overheating for no good reason. Something has to have happened to precipitate all of this.


I kind of agree with you... I do know that he drives only 2 miles to work and back Monday through Friday. He may have an occasional twice a year 2-3 hour drive but thats about it. Many short trips may have caused whatever is going on.
 
Could a dirty/plugged up throttle body cause oil backing out of the dipstick tube?

This statement by a mechanic does not sound like it would cause this.
 
The throttle body cleaning suggestion doesn't make sense - unless the mechanic wanted make a quick buck and not really address the issue.
Every engine has a certain amount of blowby - combustion gases escaping past the compression rings and raising the pressure inside the crankcase. Generations ago, the crankcase was simply vented to the atmosphere. Now, the crankcase is vented back into the intake of the engine via the PCV valve. Excssive pressure from excessive blowyby will find any point to escape. The most likely point in most cases is the dipstick tube. Crankcase pressure forces sump oil up and out of the tube.
Have your friend get a cylinder leakdown test. That will isolate the cylinder(s) that's causing this condition.
 
I am leaning towards the rings being worn or carboned up/stuck. Maybe Kreen will help if it is the rings. If the compression test is bad then old Betsy may be singing the blues...
 
No issues at all with overheating... My friend saw the engine light come on not the temp light... Dah...

BUT the oil is coming out of the dipstick tube. LOTS of carbon in the oil fill hole... Its filthy. I did pour Kreen in the motor oil a few days ago... Also had some Redline SL-1, so put that in the gas tank. Hopefully in the short term this will clean it up enough to maybe stop the oil squirting out of the dipstick. I am hoping for the best.... Maybe a long term Kreen cleaning. BUT I have my doubts.

Going to also try and do a intake/manifold cleaning and probably will just use Seafoam through the brake booster line. May just pour it through the top of the carb... Not sure if this will do anything but will give it a try.

Probably not much else to do but tear into the engine but my friend really does not want to spend the dough... Lets say a prayer for old Besty. It may be to far gone.
 
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I would do a Auto-Rx or Kreen of the engine via adding it to the oil. Be careful of how much you pour down the carb. Its possible to hydrolock an engine that way. Doesn't this engine have a TBI? My 1993 5.7L Suburban has TBI. Maybe its not a 5.7L.
 
I will take a close look but you may be right. The air filter was removed and I just briefly saw the carb.... Since you mentioned it, pretty sure it is TBI.

I did buy both regular Seafoam and also the foam with tube...

Should I just use the foam and spray it in the top air intake/throttle plate? OR remove the hose from the brake booster and slowly pour in reg Seafoam? Could be hard to get the hose off, due to age... Thanks.
 
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Originally Posted By: Boss302fan
I will take a close look but you may be right. The air filter was removed and I just briefly saw the carb.... Since you mentioned it, pretty sure it is TBI.

I did buy both regular Seafoam and also the foam with tube...

Should I just use the foam and spray it in the top air intake/throttle plate? OR remove the hose from the brake booster and slowly pour in reg Seafoam? Could be hard to get the hose off, due to age... Thanks.


What are you trying to cure with SeaFoam?
 
Hope to clean up the carbon deposits from the intake and combustion chambers... Not getting a lot of vaccum though. Did replace the PCV valve a few days ago.
 
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pull the tbi off and clean out the vacuum port for the pcv.
its packed tight.if you are lucky the sludge will stay on the gasket and simplify the job.clean out the hard plastic line too.
give it a new fuel pressure regulator too.make sure the kit comes with the spring.yours is likely broken.blowby rots it when the pcv clogs.
 
The lines look good. The vacuum was also fine and I was able to do the cleaning of the throttle body using the PCV line. The engine does run a lot better/smoother.

The Kreen may be doing some cleaning because the oil does not back out of the dipstick as much as it did a few days ago. Now the engine has to be above around 3200 rpm's before we see some oil spray out. Hopefully it cleans up enough soon so the oil stops backing up completely.

It is going in on Tuesday to a mechanic that we know for a checkup... I am thinking it may also have a possible manifold gasket leak. The overflow tank looks really dark like oil may be getting into the coolant... He is now willing to spend up to around $1K to keep her going another year or more. A lot of good trips with this truck. Hate to see it come to the end of the road.
 
What do you guys think it will cost my friend to have a mechanic replace his manifold gasket and cleanout the radiator/coolant? Not sure if it needs it bit I suspect it may. Thanks..
 
Originally Posted By: andyd
A good chunk of the 1K$ allocated. Prolly a lot of deferred maintenance, age and miles issues to resolve.


I agree...
 
Update...

The burb is running much better and not losing any oil out of the dipstick tube. We did replace a few hoses along with the PCV.

Just started the second 1K oci with Kreen and Pennzoil 10W30 HM oil. This 5.7 GM engine is runnning much smoother/quieter then it did before we used Kreen. I am assuming that Kreen is doing its job and cleaning up the rings, etc.

Flushed all coolant and replaced the thermostat. Does not overheat...

Also replaced the spark plugs and wires. While replacing the old plugs we noticed some loose carbon on a few of the drivers side spark plugs... All old plugs were very worn out, wow... LOL. Can not believe the truck even ran with these plugs. LOL.

Believe it or not, but this old Betsy may last past 300K...
 
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When you had the plugs and wires replaced, did you also have the distributor cap and rotor replaced? They should always be replaced when plugs and wires get replaced.
 
Originally Posted By: artificialist
When you had the plugs and wires replaced, did you also have the distributor cap and rotor replaced? They should always be replaced when plugs and wires get replaced.


No, I did not... I'll check them out next time I look at his burb. Thanks.
 
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