overheating G60, the final straw!

[potatonet 0]

ok if anyone has been here for the past yea we all know my G60 overheats... I have replaced everything, EVERYTHING! The fan, the radiator, the switches, the thermostat (twice), the heater core, the hoses, the flanges (4 of 'em), the water pump, the headgasket, the fan wiring harness, coolant lid, coolant resovoir, the relays for the fan (all 3), the oil cooler, I simply can not figure out why my car overheats! let me explain, maybe someone can simplify this for me.

 

I go on flat road, floor it get to 100 temp shoots up to the max and stays there for a while, I will remind you that the coolant is just filled and properly too. takes a while to get back down, then its stable at about 180, the thermostat and fan switch temp, Go up a hill the temp climbs up, not even flooring it! floor it and it peaks, it only takes about 20-30 seconds of flooring it for the thing to overheat, cant even do a smog test without overheating!

 

I go for a drive, 30 mins, come back after a thrashing and the coolant light goes on, the water bubbles out of the coolant container this is where I am losing coolant, If I had a cracked block the coolant would be emptying out on just a trip to work, so I know its not that, the head was rebuilt completely and there are no divets in it at all, there is no coolant in the oil or oil in the coolant, coolant is perfectly clear. I can drive for about a month under normal conditions without running out of water, this is me accelerating at almost every stop light but only going up to the speed limit.

 

ANYONE, PLEASE HELP ME, I AM SO FED UP WITH COOLANT ISSUES!

 

btw my friends C230 sports coupe can do everything that mine cant we tested each car side by side on all tests, his got to a max of 189 degrees (the hill test), so I know something is wrong, I am running a lot of boost and a lot of fuel but this shouldnt make it overheat.

[stevemac 0]

Was the cylinder head "pressure tested" when it was rebuilt (could be cracked) ?

 

Does the engine overheat if you leave it to idle on the driveway ? Start the engine from cold & leave it to idle up to temperature so that the cooling fan cuts-in, while watching the temp gauge.

[potatonet 0]

the cylinder head was pressure tested and is not cracked or warped. will do that test tonight and post results this evening.

[potatonet 0]

ok I let it idle for about 10 mins or so and I got it to about 210F or 100C, and the fan didnt turn on.... =-/ I think the BRAND NEW 18 dollar thermoswitch doesnt work! I tested the wiring yesterday to see if it was that, the wiring is fine and works flawlessly, there is a 12V relay system on it which works as well, I tested the wiring using the thermoswitch plug, cross the wires and voila it works, that means that I need a new thermoswitch, a very very low temp thermoswitch! OK lets just say that if my thermoswitch doesnt turn the fan into full blast mode when I am flooring it, would this lead to the coolant overheating and bubbling out of the top of the reservoir? roughly 14 psi and lots of fuel included in the mixture too.

[stevemac 0]

I'm no expert but the thermoswitch may not be the only problem. This switch usually activates when the car has little or no air-flow through the radiator. When the car is moving along the road, the ambient airspeed usually is more than enough to keep the cooling system "in check" without the need for fan assistance.

 

If the car is overheating while you are driving it (not stuck in traffic) this thermoswitch is very unlikely to be the only problem.

 

 

What's the oil temp & pressure ?

 

Friction generates a lot of heat & oil / lubrication problems often have a knock-on effect of generating excess heat in the cooling system.

[bix 0]

Probably, a dumb suggestion but have you checked the plugs to see if its running lean?

[potatonet 0]

actually its running rich, so I have plenty of fuel, oil heat is about 200F 95C I have a mocal oil cooler that is gigantic, pressure is max of about 80 psi(about 5 bar). it overheats when I punch it, no other time just when I lay my foot into it. I really need an AFR gauge.

[stevemac 0]

Longshot here - does the "full throttle switch" (pin switch on top of the throttle body) work okay ?

 

Had a recent problem with mine & turned out to be a duff full throttle switch.

 

If this switch is knackered, your engine will run very lean & get hot at full throttle. Easy to test with a multimeter.

[potatonet 0]

tested the full throttle switch in accordance with the bentley, at no throttle it read 000 which means it was continuous and at throttle wide open it read 1200 which means I dont know what... is this bad or good?

 

I used the bottom 2 terminals in the 3 terminal setup as the bentley doesnt show which terminal goes with 1,2,3 for the diagram. =-/ I could have tested the idle switch.... >=-(

[stevemac 0]

Test the switch by pressing it with your finger, then you'll know you're testing the right switch.

[potatonet 0]

using the top 2 pins, and in a different test the top one and the bottom one I got good clean results for test, continuous at open throttle and infinite at 0 throttle. what I am guessing is that my radiator has a hole in it, a small one that seeps coolant out, I can see white stuff over the front of the radiator and I havent spilt coolant there in forever. I washed it off and am going to see if that cleans it up a bit, the test will be soon. I think this might be what it is, though the radiator is new.... stupid american made products, doesnt even fit right =-(. guess I'll have to get the one from Germany rodded.... =-/.

[potatonet 0]

ok so after the temperature sat at 95C while driving on the freeway while its 12C out side then having the water light flash at me when I just filled it, I come to realize there is a hole somewhere, air pocket is being formed and thats whats making me overheat. I am looking at replacing the flange on the side of the head again.... first we'll have a look at that thermostat flange tho.

 

If my car had a leak somewhere, when i hit the gas would the temp rise?

 

pressure should cause the car to leak more water creating an air pocket, so I think it should.... =-/

[MFryJSY 10]

I know this is a really old thread but I would like to know if you ever found a solution for your overheating.

 

I recently bought a G60 that had a stage 4 supercharger fitted and my oil temps get very very high (scarily high) it doesn't currently have an oil cooler but I have a mocal cooler that i will be fitting tomorrow. Basically on a standard drive no booting just really low revs it will get up to 80C (oil temp) in about 10 mins then go on to 120C (oil temp) water temps stay well within their limits no problems there... When I fit the mocal I will also do a full oil/filter change and i'm replacing the oil with Mobil 1 15W-50 Fully synth the thickest stuff I could find. Hopefully this will sort out the problems with the mocal but my issue is that even with the cooler (which is a 16 row mocal said to drop temps by 20C) my oil temps will still peak at around 120 and run at 100... does this sound normal? Even with a stage 4 charger?

 

Any help would be much appreciated :)

[Riley 0]

Mobil 1 15W-50 Fully synth the thickest stuff I could find

 

I'd stick with the synta silver OE spec oil. 10w40 semi-synthetic, it's spec'd with the oil feed to the supercharger in mind. I'd check your oil temp sender firstly (Replace for new) and go from there.

[Supercharged 2]

Yep - advice above is spot on - that oil is way to thick for a G60 as the charger is fed from the engine oil pressure.

 

Look at the sensor, wiring and oil pressure. If the water temps are ok I doubt there is anything major wrong with it!

[MFryJSY 10]

Thanks for the replies... Unfortunately I had already bought the oil... Is there any problem with using 15-50? I did check as many threads as I could find and people were recommending it... :/

 

You say it's used to feed the charger forgive my ignorance but what is that for exactly? Just to supply oil to the charger? Also any real way of checking oil pressures or would I need to fit a gauge? It is something I was looking at anyway just not something I can afford right now... Thanks again though guys really helpful :)

[Supercharged 2]

5w - 40 is what VW recommend for this engine - most of us use 10W-40 though...

 

A 15w oil is really too thick i'd say, especially at this time of year!

[Riley 0]

You could have a local garage check the oil pressure for you, although can't beat a permanent gauge when you can get one. And yep the oil is fed via a braided line to the charger bearings. The line is sized both in length and internal diameter to regulate the pressure to a certain extent.

 

If you struggle to find the synta silver oil, I always use Vwspares for it, fantastic service and prices. > http://www.vwspares.co.uk/product_info.php?products_id=1137

 

I'd look at getting a new temp sender (Small one on front of oil filter head) and then see how you go. As soon as possible really.

 

It would be worth checking the sender wire too, because it works through earth so a slightly iffy end/connection could be causing higher resistance/incorrect readings.

Edited February 6, 2013 by Riley

[JMC 0]

Also bear in mind that if you use thicker oil and fit an oil cooler, the oil wont warm up as much so it'll remain more viscous (massively oversimplifying it there but the essence is right). With the G60 you're supposed to let it warm up before booting it, presumably one of the reasons being if the oil is too viscous it can blow out the oil seals.

[Album56 0]

Oil temps of 100 - 125c are normal for a fully warmed up G60 depending on how its being driven, ambient temp etc. Mine has chip/68mm pulley without a cooler & is 110-120c for normal driving & its been the same for 19 years. The most important thing is regular oil/filter changes & good quality 10/40 oil.

[Pickard1 0]

when I had my g60 oil was 100-120C with the normal pulley and 120+ with the 63mm. its mainly pully size that will drive the oil temps up I think rather than what 'stage' the charger is at. Once my mocal was fitted I couldnt get above about 106C no matter how I drove.

 

The oil to the charger lubricates the bearings. its these bearings seizing that snaps the timing belt and explodes the charger, so the correct oil is essential. Synta silver served me fine in conjunction with the mocal cooler.

[MFryJSY 10]

So... considering it has been a while! haha Thank you all for the responses! It's definitely been up and down this year! Had to fit a new clutch because the clutch slave decided to go pop and **** clutch fluid into the clutch housing... no more clutch... Other than that, fitted new Mocal oil cooler ran it with 10W-40 as you guys suggested and all has been well :) Or at least it was until my engine dropped due to the front mounting not being done up tight enough (silly error by mechanic mate) and putting a nice big hole in my oil filter and proceeding to **** oil out all over the road. Luckily engine was all ok and I shut her off quick enough... After a quick trip the the garage and new oil filter and mounting done up right everything is good! Temps are back to about 96-110 even when driving hard so very happy. Thanks all of you for the help :)