Help ... V35 250gt Overheating Big Time !

[Fanta R33GTR]

My 250gtm is overheating .. .help.

this is what happens.

when driving with load on the engine (e.g air con on or going up long hills) , the temp get up to about 3/4 way. Normally sits at around just below 1/2 way. Under normal driving without the air con on and flat motoway / city driving it stays at normal temp. You can sit on idle without overheating.

Doesn't seem to be related to the air con as I can replicate the overheating by driving around with the brakes slightly on to simulate load.

I've had the car 2 years.

Engines done 55K and been serviced regularly

It just had a full service a few weeks before the problem occured. New oil and oil filter and air filter etc.

Didn't touch the cooling system. Oil is the same thats been used for last two years - magnatec and level is good.

I flushed coolant after the over heating problem occurred.

My wife got it so hot going up hill with 5 ppl in the car that the coolant overheated started to pour out steam from the top of the expansion/reserviour tank.

checked all the fuses and coolant pipes. no leaks.

this 250gt has no additional radiator fan part from the main one attached to the engine.

what could it be ?

Edited December 11, 2009 by Fanta R33GTR

[n15m0]

I would be taking it to the mechanic that services ur car asap. Might be a faulty thermostat. have u checked ur radiator fan is coming on?

[GoldV35]

I think its unlikely its the thermostat, because the only 2 faulty conditions it could have are either stuck open or stuck closed. If it was stuck closed, then you wouldn't get boiling coolant steaming out of the overflow tank, as it only gets coolant from the radiator. If it was stuck open, then it definitely wouldn't overheat.

Could also of course be the thermo fan, but I wouldn't have thought it would be an issue if you are driving, as that usually has enough airflow to cool without the fan.

I'm leaning more towards a water pump issue, either way, take it to a mechanic asap, then let us know if I got it right

Edited December 11, 2009 by GoldV35

[V35_Paul]

+1 on the water pump

[Fanta R33GTR]

I would be taking it to the mechanic that services ur car asap. Might be a faulty thermostat. have u checked ur radiator fan is coming on?

this car has no additional fans. Only the one big one attached to the engine. I know some cars also have another one on front of the air con radiator, but this car only has the one.

[Fanta R33GTR]

I think its unlikely its the thermostat, because the only 2 faulty conditions it could have are either stuck open or stuck closed. If it was stuck closed, then you wouldn't get boiling coolant steaming out of the overflow tank, as it only gets coolant from the radiator. If it was stuck open, then it definitely wouldn't overheat.

Could also of course be the thermo fan, but I wouldn't have thought it would be an issue if you are driving, as that usually has enough airflow to cool without the fan.

I'm leaning more towards a water pump issue, either way, take it to a mechanic asap, then let us know if I got it right

is there a easy way to test if to see if it is the pump at fault ?

[The Max]

is there a easy way to test if to see if it is the pump at fault ?

From a cold start (so you don't get hot coolant blowing up in your face), take the radiator cap off and check if you can see the water flowing. Gradually accelerate and the water flow should increase with it. Check for any water dripping from the engine which would indicate any leaks from the water pump itself or possibly a blown welsh plug.

If your radiator fan isn't working, your car will overheat at idle after about 5 - 10 min and you'll know about it.

Worst case scenario, could be a blown head gasket. Happened in my old Maxima like that once.

[zei20l]

its probably easier to check/change the thermostat than stuff around with the water pump. which will probably whine if its a problem

if your thermostat was stuck closed, it CAN spit out the overflow tank as the pressure build up forces the coolant out anywhere it can

but before doing this, dump all the coolant out, and refill the system and bleed it properly! there will be a bleed point on one of the flanges. it could be you just have some air stuck in the system. turn on the heater (on full) and run it like that for a while too.

[Fanta R33GTR]

yeah...... it has a 3 year warranty from the dealer, so I dropped it into them and will let them sort it out. Not much i can do.

Thanks

Edited December 14, 2009 by Fanta R33GTR

[wabbo69]

yeah...... it has a 3 year warranty from the dealer, so I dropped it into them and will let them sort it out. Not much i can do.

Thanks

Is it fixed yet? and if so what was the problem please?

[Sakthi25]

Hi,

I seem to have similar issue, pls help out by posting what did you do to rectify this

[scotty nm35]

The cooling system probably needs to be bled correctly, it is quite difficult to get all the air out. There are a few threads on the subject, here and in the Stagea section for M35's

If it continues or reoccurs, perhaps there isn't enough anti boil coolant in the system, and the water is flash boiling in the head and around the bore. (these run 95-100 degrees on a cold day) Drain and fill with the recommended coolant percentages and re-bleed a few times once it's cold through the rear bleed point only. Obviously you would be checking the thermostats operation while the coolant is dropped, by testing it in a pot of water on the boil, and replacing the radiator cap, just in case.

If you still have issues, you could have a blown head gasket... I have seen it a few times.

[Jermaine James]

I just recently changed my high pressure pump and this problem started a week ago when it blew a hole on the top tank of the radiator. The engine runs for 5 minutes then coolant starts coming back as the water pressure builds up. It even cracked my radiator and was sparing the water from there. I just changed the radiator because of that.