car overheats
 

The car has a new waterpump already installed about 30 miles ago, has plenty of coolant, a new thermostat as of yesterday and a slimline fan that is working. The car drives perfectly fine, but sometimes the temp guage randomly goes higher. It can be right in the middle, jump up to the higher mark on the guage and out of nowhere just fall back to normal. It doesn't get to the red on the guage, but it is close to it. The idiot lights turn on (battery, coolant) as it is hotter. I don't think another fan would really help as it was driven at 9:30 last night and it wasn't too hot. Coolant isn't leaking either and is full. Any ideas?

Re: car overheats
 

Im not the smartest guy but maybe the sensor is messed up. Have you checked the connection maybe its wack. Like I said I dont know much but maybe this will put a thought in a some who know exactly what they are talking abouts head.
Mike

Re: car overheats
 

It is connected right. I wouldn't even know how to check if the sensor is messed up though.

Re: car overheats
 

Check your belt tension to make sure that its not slipping. Does the car have a front mount of anything obstructing the flow of air to the intercooler. And I know you said the fan is working but how do you have it wired in? Is it hard wired with a toggle switch or into your existing wiring?

Re: car overheats
 

Could be a large air bubble trapped in the system.

Re: car overheats
 

i was always currious how would you go about removing large air bubles out of the cooling systems?

Re: car overheats
 

Burp it.

Re: car overheats
 

buuuuuuuurrrrrppppp. The bubbles are out now. Does letting it run with the thermostat housing cap off get bubbles out? The car has a big greddy FMIC and the fan is wired to the original harness. The high and low were both wired into it. What belt tension should be checked? I know when I start driving it, one of the belts squeels a little when I shift into gear. Do you think the belt might be slipping slowing the waterpump down?
thanks

Re: car overheats
 

Use a logger of some sort and monitor the temp. If it's erratic that would mean the sensor is bad.

Check the tension of the only belt that's on the water pump pulley...

Re: car overheats
 

Yeah thats the belt I was talking about, who knows maybe when a load is put on your alternator it will slip causing the water pump not to function properly? Erratic temps does not always mean its a sensor. I had pretty erratic temperatures in my 2G after I put my Apexi Skyline FMIC in it. The temp would jump up past half and then cool down on its own. I just figured it was because of limited airflow that the radiator was seeing because of it. Then when the fan would kick on then it would go back down to normal.

Re: car overheats
 

Are you running the AC? That will also cause the temp to rise.

Re: car overheats
 

The ac was removed and the car keeps heated when the fan is going. I let it sit a few minutes to see if it would get to the red, but it just stays at the high mark. I will try to see if I can find the pocketlogger when I get home from work tonight. I cant use mt dsmlink right now.
Thanks

Re: car overheats
 

I'm having the same issue. I hope more peaple chime in about your issue so I can fix my car too! (Not trying to steal thread haha, I'm just along for the ride)

Re: car overheats
 

I guess James posted all of this under my name... I tried letting air bubbles out by running the car with the cap off for 1-2 mins when the gauge would fly. The fan is working (on) when the car is getting hot. FYI, there are two belts that run off the water pump. One that runs to PS and another that runs the alternator and crank. I will check the tension for him.

Re: car overheats
 

We bleed the system by letting the car for a while with a big funnel thing full of coolant mix attached to where the radiator cap goes. What is your coolant mixture like? You should be 70% water/30% coolant at the min with this weather. You could go even more with the water percent. Don't run pure water though on a street car, it can ruin the water pump due to a lack of lubrication. Your radiator could be bad too, make sure there aren't any cooler spots on it.

Re: car overheats
 

I have a special funnel that I use to get the air out.
Is it a NAPA water pump?
How is your coolant cap, It could be leaking into the overfill the system and not holding presser.
Is your timing correct?
Try switching the cooling fan relay with a different one.
Try a different thermostat.

Re: car overheats
 

The fan works. It is a napa pump I believe. Timing is set fine. It is a new thermostat. Radiator cap holds pressure. I would guess his mix is close to 50/50, not sure though. He put it in but it was fine... How long to bleed the system??? I do not want the car to overheat while trying.

Re: car overheats
 

New does not mean good. New stuff goes to shit all the time. Especially NAPA stuff in my experience.

Re: car overheats
 

How do you know the cap is holding pressure? do you have the overfill hose off?
What happened that started the car overheating in other words, what did you do to the car last before it started to over heat off and on. Was the car overheating before the new stuff?

Re: car overheats
 

I assume it is holding pressure because it isn't losing any coolant what so ever. The overflow hose is connected. The waterpump is a rebuilt stock one from bumper to bumper, not one of the really generic ones. The thermostat we got yesterday is from there also. The other one I pulled out looked different. It had the cylinder thing going down with a spring on it. The new one had the same top part but it also had a bottom part that looked the same as the top that was a little thinner. It was a lot longer than the one that was in there and thepart that sitcks out farther can be pushed in and out. The first one was solid. I was thinking it might have came off the first one, but it looked like it didn't have it. The car didn't overheat until I did the 6 bolt swap. I assume timing it good because Mike did it and base timing was set correctly. I will try another relay.
Thanks for all the help so far.
This is James again under Carlos's name.

Re: car overheats
 

Sorry about the relay thing, a relay either works or not. I was thinking the fan my not be coming on sometime.

Re: car overheats
 

We are bringing it in to a cooling and a/c place on monday to have them figure it out. They said they could figure it out.

Re: car overheats
 

All this posting is not me. It is slowbubble car too lazy to log out.

Re: car overheats
 

Ok, I looked at the car for a few minutes tonight. I started it up and let it run with the radiator cap off. After 10 minutes, the car was still right in the center of the gauge. I sat the car at a constant rev for a little to warm it up more and I noticed that when I reved the car, the coolant level would lower in the water neck. When I let off the throttle, It would come up to the top and dump a little out. When the car was heated up more, I tried it and some white shit came up (possibly little bubbles) and some larger bubbles came out. This happened each time when the car was warmed up. After about 20 minutes, I shut the car off and the coolant, which was at the top of the water neck, dissapeared and was not visable anymore under the radiator cap.

My original guess was that the car has a warped head. Comp was 140-140-130-90. James blew coolant past the HG on a pull at 25psi. My guess is that when the car heats up, air is sucked into the coolant passages by the HG. The car has ARPs torqued correctly and blew coolant on the second pull. Any second opinions???

Re: car overheats
 

Actually air is pushed into the coolany passages, not sucked. 140psi compared to 13psi.....

And it's actually quite common for a DSM to blow a headgasket like that. Considering your compression numbers, I would doubt that the head needs to come off, shaved a touch and new gasket.

Another way to verify this:
With a good radiator cap, fill the rad neck full when cold. Fill the overflow to low mark. Drive the car for a couple days. Then when it's cold again, if the overflow is full, but rad. neck low or empty.....HG.

Wiz

Re: car overheats
 

If that head gasket is blown it will cause it to overheat. Another possibility is the thermostat, get a real mitsu one. I have gotten several new ones from regular parts stores that were junk when new. The last thing would be a new radiator cap. If those 2 don't do it, then it is probably the HG.

Re: car overheats
 

So you don't think the car needs a new HG? It was tuned fine and on the second pull blew out with 1.83 counts of knock. We tightened the headstuds a little and it held on the same boost and tune. I am pretty sure the neck gets lower, but the overflow stays the same level but we will check again.

Re: car overheats
 

I will try to get another thermostat and I will try another radiator cap tonight.
Thanks

Re: car overheats
 

No, it is a good possibility that the HG is blown, but I would try the easy stuff first. No point in pulling off the head to find out the thermostat was bad!

Re: car overheats
 

A bad thermostat only causes 2 things:

Overheat due to lack of flow (stuck closed or opens late)
Over cooling due to stuck open thermostat.

The water level going up and down when you rev it is a great indicator of a working water pump.

Air bubbles can only get from the headgasket. And other place where coolant would leak would be an external coolant leak. Not bubbles in the coolant.

Rad. cap is a possibility, BUT you said that you had the cap off and then started seeing bubbles. Kinda obvious in my book. A bad rad cap will cause the high overflow/low rad neck situation. Try that first, but I would expect a "blown" headgasket.

I call the other hg failure a "leaking" headgasket. That is where coolant is sucked into the cylinders and then burned. Hence, white smoke and miss. It also slips by the rings into the oil pan.

Wiz

Re: car overheats
 

I am pretty sure the HG is the problem. I might pull the thermostat out and drop it into boiling water to see if it opens to see if it is fine, but I am planning on replacing the HG anyways since it was blown out the 2ng pull. We torqued the head studs to 95 try to seal it again. It holds during boost, but I am guessing it still might be the problem. My brother said there was white stuff coming up with the filler cap off so I am pretty sure it is the HG. I am going to make sure the head isn't warped before I put it back on to make sure it isn't the reason it blew out in the first place. The car was tuned pretty good so I have no idea how it blew out in the first place.

Re: car overheats
 

Just take the thermostat out and run it.

Re: car overheats
 

This is not the only way air is introduced into the system. Granted he has a new waterpump on it, but if the seal goes out in the waterpump it will introduce all kinds of air into it with very minimal external leakage. The only leakage seen when the seal is bad (or the shaft of the pump is grooved) is after it's shutdown. And then it sometimes is only a tiny bit that doesn't make it all the way to the ground.

And it's not recommended to rev the engine with the cap off. The radiator cap is a two-way valve for that purpose. The system will push coolant past it at a set pressure. But when the thermostat opens, it draws coolant back into the system via the little poppet in the center. You can let it idle with the cap off, but use the techniques that Shane and those were talking about with the funnel to keep the level always above the engine so it is never starved for coolant.

I agree with Jet, eliminate the easy stuff first. Take out the thermostat and run it to see if it does the same thing. It could be that the thermostat sticks a little and then opens up, thus creating erratic readings. But it would probably be pushing the excess coolant out into the overflow. It could be just enough that it doesn't overflow out of the bottle before it gets sucked back in.

Re: car overheats
 

The car still overheats with no thermostat in it. What would you do? HG? I am pretty sure coolant gets sucked into the overflow bottle but doesn't get pulled back it.

Re: car overheats
 

Yep, it sounds like a minor HG problem. As long as the radiator cap is sealing well and is good, then that is probably what it is.

Re: car overheats
 

Thanks