urgent overheating query.. Possible causes?

[bristolbaron 10]

I've just had a call from the buyer of my G60 to say it's chucked its water out on the motorway.

 

Car had done approx 110 miles at 70-80 mph, with water temp at 80-90 and oil temp at 110-120.

 

The water light started buzzing and shortly after oil light and buzzer came on.

 

He managed to pull in within about 30 secs and the car then chucked all its water from the expansion tank.

 

The top hose apparently felt hotter than the bottom at this time.

 

The oil cap looks normal, with no gunk.

 

Anyone have suggestions as to what could cause the water to suddenly drop?

 

Fan was kicking in fine before, it's had a recent new water pump, samco hoses, radiator, rad thermo switch etc.

 

I can't think of anything that would cause it to suddenly jump from 80 degrees to overheating?

 

He's currently waiting for the RAC.. Not the best start to Corrado ownership :(

[P3rks 11]

Thanks Baz,

 

Well, RAC came out and had a quick look in the pitch dark, filled up the coolant again and it started fine, no flashing lights, no nasty noises or suspicion of head gasket or worse.

 

The think it's either the thermostat, waterpump or more than likely a loose/split hose. All We could tell was the coolant was everywhere around the expansion tank.

 

When we filled the car with water and drove it onto the flat bed; removing the car there was a puddle of water under the expansion tank side of the car. Probably a leak (I hope) or that could be remnants of the coolant pouring out from boiling over previously. Who knows?

 

Either way, when removing the car from the flat bed the coolant light was flashing again.

[boost monkey 0]

Ok.

 

A loose or split hose you would notice and most likely smell, as G12 smells like sweets and due to the system pressure it'd be coating other things under the hood.

 

Thermostat fits a "hot top hose, cold bottom hose" scenario. Waterpump also fits. When my pump went, it constantly overheated and boiled all it's water out of the tank overflow which would explain why it was pooling underneath there.

 

Best bet is to swap the pump AND stat. I'd also recommend going for the solid water pump pulley from a mk2 golf, and not the clutched item. This is what failed on mine.

 

hth,

 

Jon.

[Rob_B 0]

Header tank cap? Will not let the system pressurise and will spill out of the overflow on the header tank. If it's an original header tank with black cap then I would replace it.

If the water is recirculating back into the header tank then the pump is probably ok.

[P3rks 11]

Right,

 

Just had a quick look, topped the water up and started the car. The pipes started to heat consistently, both top and bottom radiator pipes started getting hot straight away. The coolant system pressurised very quickly and the pressure built and built. You could see the water rise. The fan kicked in as it should. But, the dash only indicated temps of around 80. There is no visible air lock. All pipes got hot suggesting the water pump is ok. The fact that both the bottom and top hoses got hot suggests the thermostat is working, or at the worse stuck open which wouldn't let the car over-heat.

 

The car was left idling for ages and the water never really overheated per say. Things weren't just right.

 

I tried idling with the header tank cap off and the water started to rise and boil over. When the car was switched off and the header tank cap replaced I could hear a distinctive hissing sound from the expansion tank.

 

I'm suspecting the headgasket has failed leading to gases in the coolant causing the over-pressurising of the system. I hope I am wrong.

 

What's everyone's thoughts on this?

 

I'm not a happy bunny at all. The car didn't even make 100 miles until it broke down.

[Rob_B 0]

Could still be the header tank not letting the system pressurise and therefore boil over. If you can hear hissing from the tank it could be air escaping as it boils up.

Are there any other symptoms of head gasket failure? Water in the exhaust? Oil in the water? Water in the oil?

The header tanks are notorious for failing, had the Same problem with mine. Replaced the head gasket and it still overheated until I sorted the header tank out

[robrado974 1]

if it was the head gasket you will have oil in water and vise verser. And it would be running lumpy. My vr did the same and it was the thermo. If you say both hoses are getting hot and when you broke down they were not , i would have thought a dodgy thermo could be the problem . regards rob .

[OSV 0]

Agreed, change cap on expansion bottle and thermostat and take it from there.

[lukeyy 10]

hey, had a similar problem on my valver, mine was a blocked water pipe, top pipe of the radiator to head, where little pipe connects to go to expansion tank, where they join, tiny diaghram in there had welded together, maybe unrealted.. but possible

[P3rks 11]

Thanks for your responses guys.. Well it's had a new waterpump, thermostat, samco hoses, radiator switch, slimline radiator and fan all very recently. Took the car out again and it's 100% overheating. No gunk in the oil and vise versa. Car runs sweet. Apart from the coolant issue. On the drive the water went to 110, oil to 140! Then the oil light started buzzing, turning the car off and on again removes this. I'm guessing the heat is thinning the oil? Also the expansion tank was hissing and water/steam was coming out of the overflow....

 

Then I went to TPS and bought a new blue expansion cap, thermostat, G12 and the two oil pressure switches for good measure.

 

I drained the coolant.. Oh wait, no coolant, just water. Removed the Thermostat... Oh wait, there wasn't one. Why would you replace more or less the entire cooling system and then remove the thermostat? So yeah, you can imagine what I'm thinking by now. Oh well, I don't think I've been done over here, just one of those things.

 

 

Anyway, I poured water down every single route of the coolant system to see if it flows, there were no blockages. I fitted the thermostat and new o-ring, filled the coolant system and fitted the new expansion cap. I let the water heat up and removed any air locks. Let the car idle and reach full temp, then the matrix flanged shattered with the pressure, must have been the weakest link. I bypassed the heater matrix for the time being and let it get to temp and idle again. All was fine for a good 20 mins. took it out for a slow drive around my area, after about another 20 mins the temp rose to about 100 and the temp light started flashing again. Far too much pressure in the system again and it's blown the expansion tank. FML.

 

I'm so ****ed off.

 

The water seems to still be returning so I think the waterpump is fine. It appears to be a new item. The car is fitted with a Rallye FMIC bang in front of the radiator. The radiator is new and looks pretty small tbh, the fan is slimline and isn't the best performance wise. Could this be contributing to the problem? Although I do think that it's more pressure related than temp.

 

I think my next step is to get the car smell tested for a headgasket. Possibly the gases are escaping into the coolant system causing the pressure. Weird thing is that the car seems ok on idle. And gets worse when driving. So either the heat from the FMIC killing the radiator or gasses into the coolant.

 

Any help or advise would be appreciated. I'm literally so upset. My last car broke down loads, 4 hard months of graft and 3 weeks after fitting a new engine so it was 100%, some pikey stole the car. I've bought this car because it was mechanically great, So I thought. I just want to scrap it and give up on cars now.

Edited July 9, 2011 by P3rks

[carrots 1]

had problem with my valver,changed everything turned out to be a cracked head

[P3rks 11]

had problem with my valver,changed everything turned out to be a cracked head

 

Wow, thanks for that.

 

But surely with a cracked head you would get cross contamination, oil burning, water burning etc?

[dannyboy 0]

How long does it take to fully pressurise? anything under 3-4 minutes on idle indicates a head gasket or as carrots said hairline crank in the head.

 

Double check everything first,sound silly but didnt you check large O-ring in the coolant cap?they can get trapped when screwing cap on.

 

You dont have to have oil in the coolant or vise versa to have a leaking head gasket.the gasket could be leaking because the cylinder pressure is overcoming the gasket slighty and acting as a one way valve(8 bar and higher cylinder pressure against 1 bar coolant)then closing when engine is turned off.

Think of it like a very small leak in a hose pipe when pressurised,then turn off water the leak stops(bit like reed valve on two stroke except pressure rather than vacuum)

 

other than that,start looking at fuelling problems-running very lean,timing too far advanced,knock sensor not working,wrong fuel grade for chip?

[Rob_B 0]

Did the fan cut in ok? Could be a dodgy rad switch not cutting the fan in. Or a crap bit of wiring where the new slim line fan has been wired in place of the old one. Non gen rad switches always fail aswell.*

I did have to change the actual header tank on mine aswell instead of just a new cap (genuine not Gsf). *Could be slightly warped and not sealing 100%. Golf mk4/5 is the way to go.*

Gutted for you mate having these problems.*

Can't rule out head issues, but fingers crossed it's not

[P3rks 11]

How long does it take to fully pressurise? anything under 3-4 minutes on idle indicates a head gasket or as carrots said hairline crank in the head.

 

Double check everything first,sound silly but didnt you check large O-ring in the coolant cap?they can get trapped when screwing cap on.

 

You dont have to have oil in the coolant or vise versa to have a leaking head gasket.the gasket could be leaking because the cylinder pressure is overcoming the gasket slighty and acting as a one way valve(8 bar and higher cylinder pressure against 1 bar coolant)then closing when engine is turned off.

Think of it like a very small leak in a hose pipe when pressurised,then turn off water the leak stops(bit like reed valve on two stroke except pressure rather than vacuum)

 

other than that,start looking at fuelling problems-running very lean,timing too far advanced,knock sensor not working,wrong fuel grade for chip?

 

Yeah, it's a brand new cap, I was unaware of an o-ring in the cap, but I'll double check for what it's worth.

 

Do you not think that the standard G60 Radiator being behind the massive Rallye intercooler could be causing temp issues? I.e. the radiator can't be be efficient enough?

 

Did the fan cut in ok? Could be a dodgy rad switch not cutting the fan in. Or a crap bit of wiring where the new slim line fan has been wired in place of the old one. Non gen rad switches always fail aswell.*

I did have to change the actual header tank on mine aswell instead of just a new cap (genuine not Gsf). *Could be slightly warped and not sealing 100%. Golf mk4/5 is the way to go.*

Gutted for you mate having these problems.*

Can't rule out head issues, but fingers crossed it's not

 

Well I have a expansion tank on order, comes Tuesday. But, the new cap did last longer than the old one.

 

The rad and rad switch are brand spankers, the fan kicks in as it should, it's performance is negotiable though; being a slim line. I'm still concerned that the radiator isn't being efficient enough, but I've done a search and people have used the Rallye intercooler/Corrado G60 radiator combo before with no ill effect (apart from a slightly higher temp). I think my issue is pressure related. What you think?

 

---------- Post added at 10:50 AM ---------- Previous post was at 10:30 AM ----------

 

Right,

 

Had a long though and I'm going to have to remove the head today otherwise the car may be sat for a while due to other commitments.

 

Is there anything else i should check today before I remove it?

[Rob_B 0]

I use a g60 rad with a rallye cooler on my turbo and its fine. I've got a slim line fan with a single speed and its all good. I do use an oil cooler though which drops the temps significantly. However, I dont think cooling is your problem.

Before removing the head, try the new expansion tank. I changed the head gasket on my 20v because it overheated. I tried a gsf expansion tank and cap before I did the gasket and it still overheated. I changed the gasket and it still overheated. I ditched the gsf cap and tank and it was fine. All it takes is a little air leak to let the system boil up. If its not perfectly sealed it will not work and boil up like you are experiencing.

Dont remove the head yet, its a ball ache on a g60, wait a couple of days for a new tank before you remove the head

[dannyboy 0]

Yeah, it's a brand new cap, I was unaware of an o-ring in the cap, but I'll double check for what it's worth.

 

Do you not think that the standard G60 Radiator being behind the massive Rallye intercooler could be causing temp issues? I.e. the radiator can't be be efficient enough?

 

Rallye intercooler+corrado rad is fine,just make sure the radiator isnt blocked or caked in Cr&p. Just remember the fan shouldnt be needed when driving on the motorway unless your stuck in traffic. Anything above 30 mph the radiator will start to cool naturally without the fan.

 

One thing i nearly forgot to ask, HAVE you fitted the thermostat correct way around? you can fit them two ways,incorrect way will lead to overheating when motorway driving and just enough to cool on idle

[P3rks 11]

I use a g60 rad with a rallye cooler on my turbo and its fine. I've got a slim line fan with a single speed and its all good. I do use an oil cooler though which drops the temps significantly. However, I dont think cooling is your problem.

Before removing the head, try the new expansion tank. I changed the head gasket on my 20v because it overheated. I tried a gsf expansion tank and cap before I did the gasket and it still overheated. I changed the gasket and it still overheated. I ditched the gsf cap and tank and it was fine. All it takes is a little air leak to let the system boil up. If its not perfectly sealed it will not work and boil up like you are experiencing.

Dont remove the head yet, its a ball ache on a g60, wait a couple of days for a new tank before you remove the head

 

Yeah, I have one on order. The car's been stripped of the head now, well almost there. I took it for a sniff test this morning and it failed, so head gasket at the best. The head is going in for a pressure test tomorrow. Fingers crossed.

 

I also think your right about cooling not being the issue, i think it's more pressure. Afterall, if it was cooling down to the radiator, it wouldn't have lasted 100 miles.

 

Rallye intercooler+corrado rad is fine,just make sure the radiator isnt blocked or caked in Cr&p. Just remember the fan shouldnt be needed when driving on the motorway unless your stuck in traffic. Anything above 30 mph the radiator will start to cool naturally without the fan.

 

One thing i nearly forgot to ask, HAVE you fitted the thermostat correct way around? you can fit them two ways,incorrect way will lead to overheating when motorway driving and just enough to cool on idle

 

Yeah, the thermostat is fitted correctly. Bottom pipe is cool when the car first warms up then it gets hot as the thermostat opens. No issues there. The fan and radiator are brand spankers. I've even swapped the polarity to makesure the fan was spinning in the right direction.

 

On that note, I measured the radiator to be 35x425x325 (metal parts only, not including the plastic ends). Does that seem to be about right for a Corrado G60 radiator?

[Rob_B 0]

Ah ok, if you have the head off then that's fair enough. Just didn't want you to go to that effort unnecessarily.

What a crap start to owning a car

[GlosterOx 0]

Double check everything first,sound silly but didnt you check large O-ring in the coolant cap?they can get trapped when screwing cap on.

 

I'm having a similar problem with my VR where it is losing coolant, it only appears to have happened since changing the expansion tank (genuine VW) - There is a rubber seal around the top of the tank where the cap fits but no O-ring on the VW cap itself.

 

Should it definitely have one fitted?

 

Ian.

[P3rks 11]

Ah ok, if you have the head off then that's fair enough. Just didn't want you to go to that effort unnecessarily.

What a crap start to owning a car

 

Yeah, It failed on the smell test so gasses were 100% in the coolant. Has to be a headgasket or cracked head.. Unless the block can crack?

 

Baz has offered me his spare G60 lump if it all goes tits up for me which is really really good of him. :thumbleft:

 

Yeah, it's a bad start, but the only way is up!

 

I'm having a similar problem with my VR where it is losing coolant, it only appears to have happened since changing the expansion tank (genuine VW) - There is a rubber seal around the top of the tank where the cap fits but no O-ring on the VW cap itself.

 

Should it definitely have one fitted?

 

Ian.

 

Well looking at mine; it has no gasket on the expansion tank, but it has one on the cap.. On the underside of the cap there is a black pressure release unit, there should be a o-ring around that. Whether mines different than yours I dunno?

[Rob_B 0]

Good positive attitude mate, I like that. I'll have a look at the expansion tank on mine

[P3rks 11]

Good positive attitude mate, I like that. I'll have a look at the expansion tank on mine

 

Cheers fella..

 

I'll get the results back today for the head. Lets hope it's just the headgasket and nothing more serious.

 

On another note what's the likely hood of the block cracking?

[Rob_B 0]

the blocks can crack as they are cast. However, I would not really expect it to happen and I'm not sure if you would see the same problems you are having. fingers crossed its the gasket and a quick fix

[Supercharged 2]

Blimey - as someone has already said I would check the fan wiring to check it's correct and also suspect any non genuine parts but sounds like it's HG issue or similar as you say... I assume when you refilled you were using the correct 40% ish ratio of G12++ to water? Running just water will obviously cause issues.

 

Running without a stat won't have helped at all - fueling must have been way off and I doubt the fan was kicking in as it should even if the switch was working fine - this has probably slow-cooked the engine taking the heater matrix with it :(

Edited July 11, 2011 by Supercharged