vr6 overheating

[markeboy2005 0]

hi all, sory to bring this one up again, but as there seems to be a hundred diferet faulty thus there are a hundred different questions,

 

i have a vr6 late 92, it allways runs hot, in trafic it contantly runs at water temp 110,oil at 110-118. the fan cuts in at around 90 cuts off then the temp creeps upto 105ish cutts in again, then up to 112 cuts in again, then creeps a liitle more and the starts to leak fom the expantion tank, then boils over...

 

i have taken to turning it off at the lights so the fan cuts in and cools it down, which it does with great effiency.

 

on the open road it runs oround 100 at 50mph - 60 mph oil at 112. if i drive around 90mph- 100mph it runs at 110 the oil at around 122

 

if on the motorway i put the clutch in and coast for a minute the temp drops to 90 and the oil fals th 105- 110 then it starts to heat up agian, i dont know if that nugget of info is any use but it might tell us something,

 

i have replaced the thermo switch, replaced the heater matrix witch blew i guess becuase it got to hot, (fidderly but made so much easyer by this forum, thanks) filled with g12+, all i can think is air lock, does running it with the expantion cap of for a bit help with that?) or dodge thermostat, incerdently the stat definatly opens but not sure how much, when the engin is at 100-110 the top hode is pipeing the bottom one is hot but nothing like the top one, is that a prob or just a well functioning rad.

 

sorry to go on, any help would be greatly apprieciated,

 

also, i found a hole in the pipe that goes from near the throttle houseing to the air box, into some sensor, i cant imagine it is related, i will gt a new bit tomorrow, but what is it and what does it do?......

 

many thanks

 

ps any pictures relating to the thermostat replacing greatly wanted,

[Supercharged 2]

Welcome to the forum!

 

Hmmmm... are both rad fans working at all 3 speeds?

 

Bottom rad hose and rad get hot?

 

Is the aux water pump working?

 

Have you changed the expansion tank cap? If not then do so asap...

[Walesy 0]

That's the problem with this...problem.

 

There could be a number of things that cause it.

 

It seems that loads of raddos in all flavours seem to all of a sudden start running hot...but not too hot. Maybe it's the rad getting worse with age?

[markeboy2005 0]

yes both fans are working, one had seised but i replaced it and they work fine now.

 

as for the speeds i must say i can only really notice 2 speeds. once at around 95 and then at around 112, obvoisly i am giving those temps from the gauge so its really a bit of a guess,

 

is there anyway of testing all three speeds,

 

as for the expantion cap i have not replaced it, it only seems to bubble over when over 112. it does seem to leak a tiny bit just before it goes... so it seems to be working, could that be at fault or are you recomending changing as a precaution?,

 

cheers

[Walesy 0]

I think they're about £5 from VAG so worth changing 1st in the process of elimination.

[markeboy2005 0]

yes the aux pump works at least if i turn the ignition on i can hear it.

 

the rad gets hot and as i said the bootom hose gets hot but nothing as hot as the top one, but i guess it is being cooled through the rad.....

[markeboy2005 0]

if they are that cheap i will replace it, thanks

[TREVR6 0]

Mite be worth flushing the cooling system if you haven't done so already

[Supercharged 2]

Yep, replace the cap asap...

 

What concentration of G12+ are you running and did you fill the system via the top hose?

[Will 0]

Regarding the thermostat - Easy to check.

 

Undo the three hex bolts on the thermostat housing and take it off. Then take it apart (more hex bolts). Pull out the stat, put it in a saucepan of water then onto the hob. Watch it and you'll see it open up at about 80degrees - if not then it'll need replacing.

You'll need to replace the o-ring gaskets when putting the thermostat housing back but they're only a quid or so each.

Had/have a similar prob with mine. Flushed the radiator (only a year old), rest of the system, checked thermostat, checked all hoses for blockages, filled with high concentration g12. Still seen temps of 110 in traffic. Was 120 at times before but not sure if the lower temps are because of winter or an improved cooling system.

[markeboy2005 0]

the coolant concentration is around 50/50, i filled it up from the expantion tank with the top hose of to let the air out and squeezing the hoses. it does seem to of had the prob beforehand though...

 

is the thermostat a quick job, should i get all the parts from german swedish, and also where should i get the cap from

[Will 0]

Thermostat's a quick job, but you'll lose a lot of the coolant as have to break the system. Would be worth draining from the bottom rad hose then re-using if you just changed it.

You can get the thermostat from GSF if it's faulty but the o-rings and gasket are VAG only but not expensive. Not sure about cap - try the GSF website but I imagine it's VAG only.

[dr_mat 0]

Recommended procedure is to refill the system via the top rad hose, iirc.

[markeboy2005 0]

anybody got a good step by step guide to changing the thermostat on a vr6, i am going to atempt it tommorrow... do i have to remove the entire housing? and does it just pull of from the pipe that goes across the front of the engine?? any guides tip much appreciated. does the cover, covering the sensors just pull off? thankyou....

[gradeAfailure 0]

Tbh mate, if you're replacing the stat, I'd splash out a few more dollars and get one of the Neuspeed ones from Awesome GTI - it'll help the engine run a little cooler...

 

Bout 2/3 of the way down the page...

[markeboy2005 0]

tried channging it, the back bolt on the housing is mashed, nore so now, so i could not get it of. any ideas

 

thanks

[markeboy2005 0]

ok so i have changed the cap refilled the system from the top hose and it is still over heating.

 

it seems to circulate ok with the cap of there is a very little drizzel at idle hardly any thing really but once i rev it a little the is a good flow

 

also how hot should the bottom hose get,? while my top hose is to hot to hold the bottom one gets dam hot but nothing as hot as the top, i guess its being cooled in the rad, so it could make sense,

 

one other thing, when i run the engine with out the expantion cap on, it bubbles over before the fan cuts in, any idea's?

[markeboy2005 0]

how long should the fans com on for when the engine is running? mine come on at 90, 100, 110 but only stay on for 15;20secs tops and dont realy seem to bring the heat down????, then is still boils over

[andy 0]

one other thing, when i run the engine with out the expantion cap on, it bubbles over before the fan cuts in, any idea's?

I don't find that hard to believe, the expansion cap is there to provide pressure in the system to raise the boiling point of the coolant. If you remove the cap the water will boil at a lower temperature, quite possibly before the fans cut in.

[markeboy2005 0]

and how long should the fans run for mine go for about 20sec and dont do much to the temp?

[andy 0]

mine rarely run for more than that

[Kevin Bacon 5]

It does sound air lock related. When the cap was off, did you notice a constant stream of coolant coming from the thin return hose? If it's spluttering, there's air in the system.

 

If it's getting too hot too quickly, it might be worth inspecting the main pump for wear.....although at £25 odd from GSF, you might aswell put a new one in.

 

In the meantime, an hour spent wiring in a manual over ride for the 3rd speed (120 deg trigger) is time very well spent. Speed 3 is immense.... sounds like a hover craft! It will reduce the water from 100 to about 80 in 30 seconds or less in a healthy system, so no need to stop the car in traffic.... it's better to leave the engine running and blast the rad with King Kong speed.

 

All you need to do is pull off the little flap covering the 3 senders in the stat housing and unplug the black plug. Cut the loom, add two wires in parallel to it and solder the whole lot back together again and plug it back onto the sender again. The other ends of the wires you feed into the car to a switch.

[markeboy2005 0]

it comes out in a constant stream, does not really come out at idle, at least it is prob trickling down the side but with a few revs it comes out.

 

down side is after trying to get the thermostat off the rear hex bolt had worn so the socket just spun, any idea's for getting out knackered bolts, i was thinking about one of thoses reverse thread bolt extrackters,

 

how can i tell if the water pump is ok, is it hard to change???

[andy 0]

Not that hard to change, I did mine in a couple of hours the other day. Bolt extractors are well worth a try, they've got me out of many a hole!

[markeboy2005 0]

cool, i reckon i might change the pump and thermostat, getting fed up of doing the coolant,

 

good pun by the way