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5.7L head gasket replacement

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'93 Chevrolet Caprice, 5.7L with 105K miles

When the engine is cold and I hit the highway, the temperature gauge shoots into the red after a few minutes. Stays there for about 1-2 mins, then T-stat opens, and it goes back to normal. I replaced numerous T-stats, bled the system and eventually realized that it is the head gasket. It throws air into the system. I can see tiny bubbles no matter how much I bleed it. This air into the cooling system makes the T-stat open a bit slow. But after 5 minutes of driving, there is no overheating no matter how long I drive, even in city driving.

The passenger side head gasket has been replaced during engine install. How hard is it to replace driver's side head gasket on L05? Is this a DIY project? I have swapped some stuff in engine bay but nothing of that caliber.

Second question, is it dangerous to drive like that, will this condition where I run for 1-2 mins with temperature in the red damage something like crack heads? Is it really overheating?

Lastly, this issue entirely goes away with 160F T-stat, but I run 195F for better mileage.

Reply to
An Metet
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Reply to
Bobo

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The water pump is nearly new, so that's not the issue. The head needs to come off. I need to know the sequence of things to remove to get to the head. Is there a good web site that shows how to do this? A book?

I have turned some wrenches, one time I even removed a whole engine but it took me about 3 days to find all the bolts and connections. Thanks.

Reply to
An Metet

I am having the exact same problem with a 92 Caprice and a 5.0l engine. If I drill a small hole in the edge of the T-stat, the problem goes away. I have raised the front of the car up high on ramps and have bled the system. T-Stat has been replaced several times and is not the problem.

The system acts like there is a pocket of air in there that collects at the T-stat housing causing a sluggish t-stat.

Here is how it fails:

Get in cold car and start driving. Temp gauge starts going up till it goes just shy of the red and then drops like a rock back to normal. After it goes through this gyration it will *usually* be fine for the rest of the trip. However, sometimes it won't open and i have to pull over and squeeze the upper hose a few times to get the t-stat to open.

Again, radiator/heater core t-stat are all fine.

I'm starting to think it is the water pump because I don't think the head gasket is blown. No oil/coolent mixing and no sweet exhaust fumes. Also the coolant level doesn't drop at all.

But like I said drilling a little hole in the edge of the 195 degree t-stat fixes the problem.

I was also thinking of putting a bleeder screw on the t-stat housing like some cars have.

Anyone have any other ideas?

Reply to
psycho_pastrami

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psycho snipped-for-privacy@yahoo.com wrote:

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I have a head gasket leaking some compression into the water jackets. The pressure inside the cylinder is enough to push air into the cooling system; however, the pressure inside the cooling system is not enough (15 PSI) to push water into the cylinder. This is probably the case with your Caprice, too. A leak down test is necessary to prove this.

It could be a cracked head, or a crack in the water jacket.

Something you can do is install a 160F thermostat. I haven't had any problems with overheating with it. The reason I ultimately removed it is because the PCM is programmed for 195F. With 160F, you would have to reprogram that computer. I hear that with 160F, you get more HP, but less mileage. I like my engine to run as hot as possible for best mileage, but 160F T-stat is a popular performance enhancement.

Also checking compression is a good idea.

Checking for exhaust in the cooling system is another idea.

In my case, there is no real easy fix, the head needs to come off.

Reply to
An Metet

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