Coolant Problems

[Yeltsew7]

If this is the wrong forum, let me know.
First off, I just bought the car. I've had it for 3 days. I have a horrible vacuum leak on my intake manifold gasket. I read somewhere that this can cause oil and coolant to mix. I just had my coolant flushed this morning, and it's already full of oil. Could this be the cause?
Next issue
If I drive for more than a few minutes, my temp gauge gets pegged on red. If I open the hood, and try to look at the thermostat housing with an IR thermometer, it doesn't ever read above 85°C. I also stuck a thermometer into the coolant and it didn't even react. The coolant and oil mixture was barely warm.

Is there a way if I can tell if the thermostat is even working? It doesn't seem to be even trying to cool the engine. I'm completely lost.

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[ForcedFirebird]

Coolant does not go through the intake manifold, so not sure why anyone would post they mix there.

Typically when coolant and oil mix in the m20, it's due to the common head crack under the camshaft - but - that puts coolant in the oil, not reversed.

The gauges in these cars tend to have the ground nut fall off the back. Tap on the dash while it's in the red and see if it's a faulty gauge - if so, simple fix (probably your case if you are reading actual t-stat housing temps).

[Yeltsew7]

I tapped on the cluster a lot and it didn't change. It reads cold when the engine is cold, but as it warms up it just continues rising. I don't know what to think. Is there a way I can read the actual resistance from the temperature sensor and convert that to the actual temperature?

I'll take a look at the ground on the cluster, but it seems to be working, just overheating.

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[EyExR]

Sounds like your head gasket is shot. I think the biggest PITA with the job is removing the intake manifold so might as kill two birds with one stone. You'll get a chance to replace your timing belt, too.

[ForcedFirebird]

If I open the hood, and try to look at the thermostat housing with an IR thermometer, it doesn't ever read above 85°C.

I'll take a look at the ground on the cluster, but it seems to be working, just overheating.

These posts are contradicting. If the head temp is 85°, then it's not overheating. Coolant always runs through the t-stat housing, but not always through the radiator/expansion. The thermostat is a diverter and keeps the coolant recirculating through the engine when the stat is "closed".

[ForcedFirebird]

Sounds like your head gasket is shot. I think the biggest PITA with the job is removing the intake manifold so might as kill two birds with one stone. You'll get a chance to replace your timing belt, too.

I leave the manifolds bolted to the head and lift the entire unit out, then lower it back in assembled with an engine hoist (or a couple extra hands). This makes the manifold bolts very easy to get to. :)

[Yeltsew7]

I just realized that I forgot to mention, when the gauge reads hot, the radiator is completely cold. Thermostat maybe?
I'll probably look into headgasket anyway.

These posts are contradicting. If the head temp is 85°, then it's not overheating. Coolant always runs through the t-stat housing, but not always through the radiator/expansion. The thermostat is a diverter and keeps the coolant recirculating through the engine when the stat is "closed".

I meant that it wasn't always reading hot, just once the engine warms up. I don't know, I'll look into it some more

I leave the manifolds bolted to the head and lift the entire unit out, then lower it back in assembled with an engine hoist (or a couple extra hands). This makes the manifold bolts very easy to get to. :)

Thanks for the tip

[EyExR]

I leave the manifolds bolted to the head and lift the entire unit out, then lower it back in assembled with an engine hoist (or a couple extra hands). This makes the manifold bolts very easy to get to. :)

Me too! :D

[ForcedFirebird]

Check the temp of the t-stat housing when the gauge reads "hot", could be a bad stat, or clogged radiator - since you have an IR thermometer, check the temp of the hoses and both corners of the rad too. The brown (or black) sensor is the gauge sender, the blue one is for the ECU, point the IR between them to get a good reading of actual engine temp.

[Steve Corbett]

I have had high temps on gauge and cold radiator and it usually is a coolant system not bled properly. There is a bleed screw on the thermostat housing for bleeding the system.

[Yeltsew7]

I'll look at that too. Today I was messing with it and the gauge would not even move up, I'm going to remove it and look at all the grounds.

I ordered a 75°C thermostat and housing. I assume that since I live in a pretty hot climate it can't hurt to have it open sooner.

Will get some readings when I can.

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