vert with menopause

[rhatmonkey]

So my vert now overheats quickly with a thermostat in it, take it out and it heats up to midline (operating temp) and stays there. The only other issue is that when it idles sometimes it starts to sputter but a little gas giving fixes that and sometimes takes a little bit to start. I had it compression tested thiniking it was a blown head gasket but it passed pressure testing (140psi across the board both hot and cold). We blead the coolant system using all the tricks ya'll have mentioned but it still overheats. We even tried 3 different thermostats but no luck. The radiator is a Koyo aluminum radiator and the fans are brushless electric fans that turn on with my accy. The water pump is brand spanking new.

Does anyone have any ideas why it could be overheating? I'm all outta ideas.

[240vert93]

New gauge cluster? Are you sure your gauge isnt just screwed up? That or maybe you're engine isn't opening up to the rad

[-RJ-]

id try replacing the temp sensor

[Eikon]

I agree.. temp sensors are cheap.. try a new one and see what happens.

Are you sure you aren't installing the thermostat backwards?

How new/old are your hoses from the rad to the engine? I've seen old ones buckle under pressure and cut off circulation.

Some cars just get gremlins.. Yours might be a thermostat gremlin. If it's operating perfectly without it.. why not just go without and move on? I know that's not the "right thing to do", but sometimes you just go with what works and enjoy the car.

If all this doesn't solve it... Swap in an SR20.

[S13xCrazy]

^^swap in a sr...what a joke

When you install the thermostat, are you positive that the little pin on it is on the top and it is installed the right direction?

[KLYPH]

If all this doesn't solve it... Swap in an SR20.

Lol.

Buy one of the venting radiator caps at discount auto. The ones that you can lift a tab and they discharge hot liquid into the reservoir.My car was overheating after the therm. change and I bought one of these. The next time it started to overheated I opened the valve and let the reservoir fill up most of the way. By the time I got home the level went down in the reservoir and the car never overheated again. I just toped it off and its been smooooth sailing.

[GoinTopless240]

Just gonna throw this out there for the hell of it... if all the other things mentioned are ok... have you done anything to effect the timing?.. To advanced and could cause a melt down (reason I say that the overheating and hard start condition). Coolant may be flowing so fast with thermostat out the keep from melt down. Just a thought. After all. We know how awesome the timing chain guides can be on the KA's.. And if you happen to check/adjust timing, remember to follow the FSM.

[rhatmonkey]

ok so just to clear up a few things...

1. the stat is in right,.. i made sure of that besides i have the nissan repair manual you guys posted....

2. the timeing has been checked, had a mechanic put the chain to a timing light and it checks out.

3. i got one of those venting radiator caps and tried what KLYPH said but that didn't help

4. the gauge cluster is accurate ( or atleast i think it is ) just based on the fact that when my temp gauge said it was at H i pulled over and the engine was steeming. [this was when my coolant was evacuated from the car when the clamp holding my upper radiator hose broke and was pouring fluid all over, didn't notice cause i was driving until the gauge went to H ]

... at this point the only thing left is a temp sensor change or just chalking it up to a gremlin....

asside from the overheating the only other issue is a sputter on idle. basically when it idles, it may start to sputter then slowly die unless i give it a little gas to keep the rpms up.

i just figure i'll run the engine until it does then swap the motor and transmission (get outta that auto).

thanks for all your ideas so far, if there are any other ideas i'm open to suggestions.

[240vert93]

Just for giggles take out the fan shroud, fan and belt and give your water pump a spin. Nothing like a seized or seizing bearing to ruin your day. Other wise check hoses for blockage, look inside rad for calcium depositing. Was the engine steaming or was the surge tank steaming. Important question right there

[rhatmonkey]

when it overheated the engine was steaming...

about the fan shroud,... i don't have one, i have brushless fans mounted to the radiator. The radiator is a new Koyo radiator and there is no calcium depositing.

I'll hopefully be taking the car to a friend on friday to get the block compression tested again, we believe the first time wasn't accurate. The going theory is that there is a crack in the headgasket where the cylinder and coolant piping meet thats small enough to push bubbles into the line but not big enough to make any smoke.

We shall see.

[240vert93]

If your engine is steaming thats bad news man. Good luck

[S13xCrazy]

140 for compression seems kind of low to me?

I thought KAs were about 175 from factory, and anything below 150 can indicate rings or headgasket?

[rhatmonkey]

yeah your right, we think that the first guy to look at it tested it WAY to low,.. obviously at 140psi it'll hold but i'm thinking it won't hold at 175psi, where its supposed to be.

i'm hopefully taking it to get rechecked tomorrow,.. pretty sure its a blown gasket though.