to overheat or not to overheat.....wtf?

[eddeb11]

hey all. eddeb11 here.
got a 92 Sonoma with the 4.3 in it. has a number of issues, one that ive been dealing with for years is that my temp gauge will steadily rise until the dash light turns on but after a few minutes of continued driving it will go back down to normal.

this is a constant issue, it will happen approximately between 5 and 10 times in the matter of a 20 min drive. it started when I upgraded and charged the AC system in 2010 due to an unusually hot summer and its been happening since.

ive replaced the upper radiator hose and thermostat. also when I popped the cap on the radiator there is some (for lack of a better word) crud inside the top of the cap, it looks like mayonnaise floating in the antifreeze, it gets so thick that I have to scrape it out to clear the top of the radiator to check for fluid.

if anyone has any idea as to why the needle goes up but then comes down and what the hell is that mayo like stuff....please let me know. thank you.

p.s. the truck will NOT overheat to the point where I have to stop. the needle just goes up and stays there for a while then goes down. also there are no smells associated and no leaks either.

 

[Molson02536]

hey all. eddeb11 here.
got a 92 Sonoma with the 4.3 in it. has a number of issues, one that ive been dealing with for years is that my temp gauge will steadily rise until the dash light turns on but after a few minutes of continued driving it will go back down to normal.

this is a constant issue, it will happen approximately between 5 and 10 times in the matter of a 20 min drive. it started when I upgraded and charged the AC system in 2010 due to an unusually hot summer and its been happening since.

ive replaced the upper radiator hose and thermostat. also when I popped the cap on the radiator there is some (for lack of a better word) crud inside the top of the cap, it looks like mayonnaise floating in the antifreeze, it gets so thick that I have to scrape it out to clear the top of the radiator to check for fluid.

if anyone has any idea as to why the needle goes up but then comes down and what the hell is that mayo like stuff....please let me know. thank you.

p.s. the truck will NOT overheat to the point where I have to stop. the needle just goes up and stays there for a while then goes down. also there are no smells associated and no leaks either.

Thank Mayo looking substance is oil mixed in with your antifreeze, being a 92. There is a good chance that your oil cooler in the radiator has gone bad and your going to have to replace it soon as possible.

Coolant mixed in with your engine oil in the crank case will eat away your bearings, at worst your have a head gasket leak somewhere. Also check your transmission fluid to make sure its not your transmission cooler that is not leaking. Coolant in your transmission fluid will also eat away the bearings in your transmission.

As for the over heating, good chance that the oil sludge in the coolant is gumming up your thermostat like your radiator cap causing at to stick. replace the thermostat and flush out your cooling system if your radiator needs to be replace. At worst as mentioned, a head gasket has failed or lower intake manifold gasket.

Keep us posted

Molson02536

 

[drwet]

I agree you have oil in your coolant and it is probably related to the overheating. It sounds like a leaking head gasket. These 4.3's are also famous for leaking intake manifold gaskets. Its not a matter of if your intake gasket will leak, but when.

 

[eddeb11]

damn... lol that all sounds a little out of my league. is there any place onlne I can download diagrams from to help with the taking apart of the parts mentioned?

 

[Molson02536]

damn... lol that all sounds a little out of my league. is there any place onlne I can download diagrams from to help with the taking apart of the parts mentioned?

Start with determining which fluid is mixing, Pull the dip stick to your transmission and check the condition of the fluid. It should be bright red without any discoloration. If there is no discoloration and the level is correct then its good to say its not mixing.

Check the engine oil for any signs of coolant mixing with it like what you have found on your radiator cap. Best to pull the dip stick to check the oil level, and under the oil cap. Moisture under the oil cap and the PVC valve is a indication also that coolant is mixing into your engine.

If your still are not sure where the leak is, drain the coolant and replace it with water until you find the leak, but don't drive around with just 100% water. The water will boil over until its all gone and then you loose an engine.

Start with flushing out your old coolant with http://prestone.com/products/car_care/cooling_system_treatments. This should clean out any oil and rust in your cooling system and then replace the coolant with water and run the engine to find where your leak is and don't forget to replace the thermostat.

Once you find where the leak is, repair the issue and then replace the water with the proper coolant. At best, it may just be the radiator going bad and the oil coolers in there are leaking in to you coolant. Auto Zone can give you the step by step instructions to replacing your radiator if thats what's bad, if its an intake manifold gasket or a head gasket, then you'll have to decide if your going to spend the dollars to have it repaired or have a used 4.3 engine installed which may be less expensive then to replacing the head or intake gasket.

keep us posted.

Molson02536