9 replies to this topic

[DaneinUS]

My ’94 850 turbo overheated last night. No warning lights came on – only the water temp gauge was in red and steam and coolant started coming out – ouch!

I let it cool off overnight and this morning tried to fill it up with water and warm the engine up again. It does not take very long before the car goes near the red field on the temperature gauge.

Before I order parts and begin a head gasket replacement (what a member in this section in an earlier post called “12 hours of hell”), I would like to have the diagnosis confirmed – blown head gasket between coolant canal and combustion chamber. Could it be anything else? (please let it be something else )

What would be the best way to confirm the diagnosis – measure the pressure in coolant system while cranking the engine, Leak test or compression test?

[jda2000]

how long was the needle in the red? did you stop driving it as soon as you noticed it? did you turn the heater on before you turn the car off, to dissipate the heat?

If you answers are : not long and yes, then the chance of a blown head gasket are low.
Start with the simple and cheap. Replace tstat and ECT sensor and start from there.

Let's know how it turns out

[Rule 308]

How about paying someone for a real diagnosis? It wouldn't set you back too much to have someone perform a block check on it and check for the presence of exhaust gases in your cooling system. If that is out of the question then try stuffing in a new thermostat and pressure testing it. If it passes a simple pressure test then fire it up a watch it go through warm up. If the needle was in the red and it was overheating I would say not to worry about the temp sender until you have diagnosed it properly. It has been my experience with the 850T's that they are very unforgiving when it comes to being overheated and not blowing the head gasket. Should you stuff a thermostat in it and it quits over heating I would still seriously consider get the block check done on it. Chances are you could simply have a thermostat that gave it up and this is why it goes right into overheat when you start it. Replacing the defective part should fix that problem but you still will not know if the head gasket was compromised by the initial over heat condition.


Rule 308

[freeskier8585]

replace the stat, then get it checked out, summed that up in 13 words....

[BlackT5]

Get the thermostat replaced and come back. I'm almost sure it will solve the problem.

[Mesoam]

replace t-stat summed up in 7 words

[Bay13]

Replace Thermostat. (2 words )

or

thermostat (1 word )

[DaneinUS]

Pheew – I might be off the hook! I did what - according to popular opinion - was the only way to go – change the thermostat. Now it seems to keep a normal engine temperature without any boil/steam stunts.

I might still take it to the shop tomorrow to have the pressure in the cooling system measured. I still can’t believe that the gasket/head would stand getting that hot. It had blown between ½ and 1 gallon of coolant out!

Thanks for your help so far!

[swsteckly]

My S80 heated up into the red multiple times (I was able to get it down all the times except on by blasting the heater) when the radiator fan failed. The last timew as the worst and happened on my way through the dealer's parking lot. It was boiling, and blew a ton of coolant (at least a gallon) out the overflow and around the cap.

I of course flushed the coolant, changed the oil, etc. Almost a year later, I see no ill effects.

[DonDavis]

This is kind of funny. I have'nt been here in some time as the 850 has been running great. Today I get home and the wife tells me the a/c quit working and "the engine made a wierd noise".

I go out and look it over, start it up and everything sounds fine. I go around the block with the a/c on and it overheats quickly. Back to the house, shutdown and the electric fan is running. I asked if that was the "wierd noise" and it was. I check in on this board and "bada-bing", front page has a thead describing my problem exactly. I was going to do the same as recommended (change t-stat) and cross my fingers.

I love this place. I'll let you know how my car turns out.

Good luck DaneinUS!! Hopefully we just have faulty t-stats!!