Overheating without overheating
 

The subject confuses me too. I have a 94 Maxima with SOHC inherited from a recently deceased relative. I am trying to sell it and don't want to drop a bunch of coin into it.

The issue is the car began spewing pressurized coolant out the cap within five minutes of starting it cold, however the temp gauge never moved off from horizontal. I replaced the cap dreaming of a cheap solution. The new cap held the pressure so well it blew the top hose right off the radiator.

I suspect the thermostat but a mechanic friend thinks it more likely is a cracked head w/ coolant leaking into the cylinders and kicking up the pressure immediately without the engine running hot. Any suggestions would be appreciated.:confused:

could it have been overfilled somehow? Perhaps the last owner went to add coolant and added too much? It seems like you would smell coolant if there were a leak anywhere, and there would be steam from the source of the problem

Do you know if the engine has been overheated before you got it,if
so it could be a cracked cilinderhead .

Zeroing In on the problem
 

Thanks for the help gentlemen.

I got the thermostat cover off yesterday only to discover that the previous owner(s) had removed it... therefore it definitely was not the thermostat stuck closed.

I am indeed afraid that this car has an unknown and shady history and the likelyhood of a cracked cylinder or blown head gasket is strong. Consulting once again my local mechanic friend, he told me that if an engine isn't showing to be HOT on the gauge but is building up intense pressure in just 7-10 minutes of running, that it is MOST LIKELY a crack in the block somewhere. It is also likely that the coolant never gets into the cylinder because of the pressure and therefore there are no telltale signs in the oil pan or the exhaust pipe. Live and learn.

Thanks again for the assistance.:bawling:

Re: Zeroing In on the problem
 

Just take the cap down to the good ole radiator shoppe. Ask them to test it. Most likely it will fail. The radiator cap is a pressure release valve, and it isn't supposed to release until somewhere around 18-20psi. If the cap is weak, it will spew coolant at a much lower, non-critical point. New caps are in the cheap.

Re: Zeroing In on the problem
 

Sounds like a real problem. Removing the thermostat is of course a sign that the car has overheated at some point in the past. If this happens to someone, they usually tell somebody else about it, and about how they fixed the problem, and what happened. I agree with your mechanic in that the engine has some relatively major problems, but would not agree that the block is cracked. 3rd gen Max SE engines have a cast iron block, and aluminum heads. You probably have a blown head gasket or a cracked head. Either problem is definately worth investigating and/or fixing. You have to evaluate other issues with the car like the color, options, ABS airbag, etc to determine if you plan to keep it..

Who knows that car may run for another 15 years..

Re: Re: Zeroing In on the problem
 

BEt it's a head gasket. often the overflow reservoir will be bubbling in this case. Wierd that it blows the cap without spewing out the overflow first.

Re: Re: Re: Zeroing In on the problem
 

What color is your exhaust? That's another telltale sign of a blown head gasket.