95 850T Blown head gasket?

iruleyounow · Post by **iruleyounow** » 28 Aug 2014, 12:15

So my heater core blew right after I had work done at a shop. Literally 30 mins after. They called a tow and towed it back to their shop. Told me they would look it over and do pressure tests etc.

They confirmed the heater core was shot, but then told me the head gasket was bad?

I've never lost coolant, I've never had one engine light come on ever. Never had any signs that it would have a bad head gasket.

I had told them to go ahead and bypass the heater core system. But it sounds to me like they didn't do that, so wouldn't that mean the pressure test would automatically come up false?

I'm gonna go pick it up and do what I need to do. Just want some input. Thanks guys!

Post by **erikv11** » 28 Aug 2014, 12:29

On these cars heater cores go out all the time, head gaskets rarely go bad without overheating. I share your skepticism.

How did they decide the head gasket is bad?

If a bad head gasket is blowing out the heater core, then there will be combustion gases in the coolant. You can check for this with a kit from the auto parts store. I would do that, if the shop hasn't already. If that combustion gas test comes back positive then unfortunately it is a very clear sign of a head gasket problem. If it is negative then there is more work to do to actually rule out a head gasket problem.

iruleyounow · Post by **iruleyounow** » 28 Aug 2014, 14:24

erikv11 wrote:On these cars heater cores go out all the time, head gaskets rarely go bad without overheating. I share your skepticism.

How did they decide the head gasket is bad?

If a bad head gasket is blowing out the heater core, then there will be combustion gases in the coolant. You can check for this with a kit from the auto parts store. I would do that, if the shop hasn't already. If that combustion gas test comes back positive then unfortunately it is a very clear sign of a head gasket problem. If it is negative then there is more work to do to actually rule out a head gasket problem.

Well I just got it back. They said they did the coolant test and that's how they knew it was bad. They also didn't put my throttle cable back on, and didnt hook a hose up right. So I'm very skeptical. Like I said I've never had an issue with any overheating or any problems with cooling or oil or anything period! Just hard for me to believe. Plus I've never lost coolant. Idk where to go from here really

Post by **RussB** » 28 Aug 2014, 15:36

When you blew the heater core and spewed out all the coolant and you continued to run the car, it's very possible that the head warped and "blew" a head gasket

iruleyounow · Post by **iruleyounow** » 28 Aug 2014, 15:48

RussB wrote:When you blew the heater core and spewed out all the coolant and you continued to run the car, it's very possible that the head warped and "blew" a head gasket

I never ran it after. I shut it off literally the moment it happened because there was so much steam and smoke from the coolant hitting the exhaust.

Post by **mecheng** » 28 Aug 2014, 15:51

Do comp test, only reliable method

Post by **erikv11** » 28 Aug 2014, 16:21

It's not that simple - just like the other tests (combustion gases and cooling system pressure test), a cylinder compression test is only useful for detecting some of the head gasket failures.

The head gasket separates three compartments: combustion, cooling, and lubrication. The breach can be between any two (or all three), and leak in one direction or both of them.

For any one test, a positive is definitive but a negative doesn't mean you are out of the woods.

Post by **mecheng** » 28 Aug 2014, 16:27

You are correct, but it is the easiest test for a diy. Everyone has a pressure gage. If your compression test is fine, check if you are losing coolant or oil or if either is contaminated. Then check if overheating. If all is ok, you don't need to go to a shady mechanic to tell you otherwise.

Post by **erikv11** » 28 Aug 2014, 16:34

Agreed, you may need to do a battery of tests so why not start with the easiest one.

Don't forget checking for combustion gases in the coolant before deciding if all is OK. This is the only kind of head gasket test that has ever came up positive for me (several years ago on a Camry with a warped head), maybe that is why I fixate on it ...

Post by **northernlights** » 28 Aug 2014, 17:15

An easy check that doesn't require tools is to fill the cooling system and run the car! Just so long as you have taken care of leaks, then this will give you an answer. If the overflow level slowly drops, then you are burning coolant due to a leak. If the overflow overflows then you are pressurizing the coolant, also due to a leak. Other than very, very, very slow evaporation/diffusion out of the system, coolant should not disappear unless you have a leak.

If you keep pouring in coolant, and it never seems to fill, then you might have a huge leak and are filling one or more cylinders! Don't do that! A hydrolocked engine is bad!

Arguably you might make it worse by trying to start it, but if the head gasket is leaking then it needs to be fixed regardless. These engines do not seem to like being run out of coolant, so even though you stopped it once the light came on and steam shot out, the system pressure was already compromised at that point.

If the gasket is marginal, and you are very, very carefully to keep it full of water, then you might be able to drive short trips for a little while, but the clock is ticking for a repair.