Overheating VR

[fla 9]

I know its been covered, the whole overheating business, but this one seems bizarre. Oil temp is nice and steady at about 85 on the motorway. As soon as I pull ino normal town driving (and thats without any traffic) the temp shoots up to about 110 with the fans tripping in at about 104. Both rad hoses get warm so the thermostat is not stuck. And as soon as there's a nice straight run it cools down quickly again to a normal 85ish, which also suggests the radiator fins are not blocked. It is literally a town run of a few minutes that causes it to heat up. Recently drained and flushed the system and refilled with G12+. Coolant level is okay.

Oh BTW, I've got a mocal through Ebay (which the To##er still hasnt posted although he's cashed my cheque, but thats another story) so when this arrives its going in sharpish. What should i do in the meantime?

Any ideas? Thanks all.

[quicksilver 0]

That seems fairly normal to me - mine does it when driving slowly after a fast run - its almost as if the engine is dumping heat into the oil and water when you slow down.

 

Mind you it always seems to settle back down to about 90 - 100 C oil temp and 90ish water temp.

[Supercharged 2]

fla, your rad thermoswitch is knackered, it sounds like its onlu coming on at stage 2.

[Supercharged 2]

fla, your rad thermoswitch is knackered, it sounds like its onlu coming on at stage 2.

[dr_mat 0]

Sounds to me like you're confused about the difference between oil temp and water temp, too!

[fla 9]

Sounds to me like you're confused about the difference between oil temp and water temp, too!

No mate, they go pretty much in parallel so as one goes up so does the other, with pretty much the same differential throughout. Its just that those are the only temp data I remember offhand.

Mind you it always seems to settle back down to about 90 - 100 C oil temp and 90ish water temp.

 

Mine doesnt. It still wants to continue increasing in temp.

Supercharged, what makes you think the rad thermostat is dead? If that were the case, wouldnt the fan not come on at all, or be running continuously?

If it needs replacing, what else do i need (apart from the obvious!)

Thanks all.

[Kevin Bacon 5]

Fla, your symptoms are exactly like what happened on an old Golf 16V of mine. Know what it was? The water pump!

 

The impeller blades wear down (plastic in the VR's case) with age, or in rare circumstances, the impeller loses it's grip on the spindle. But either way, at high speeds there is enough pumping pressure and wind through the rad to cool the coolant. At low speeds, there isn't enough pumping pressure or enough wind force through the rad, so the temp rises and rises.....

 

That's my Friday afternoon theory anyway and at £28 for a pump (metal blades) from GSF, it won't hurt to try a new one. It's an airbox out, jack engine up job though, about an hour.....

[CoxyLaad 0]

provided you can get the bolts out of the water pump pulley - which I couldnt :mad:

[Kevin Bacon 5]

Aye, tis a pain that....but my tried and trust method is to leave the belt tensioned, 'crack' the bolts with a hammer and allen key after a long soak in plus-gas and then bob's your funcle....

[Funkster 0]

It can really be done in an hour? The manual makes it look more involved. I'm half tempted to change mine this weekend 'cos I'm sprinting the car on tuesday and would like to alleviate any cooling system paranoia.

 

I noticed on a hot day last week that although it would cool on the motorway, if I let the temp creep up to 100 in traffic (where the fans would catch it) and then moved away at say 45mph in clear air, it wouldn't get below 95 again. Both rad pipes seemed to be the same temp at this point, but it's hard to tell.

 

Pesky hot VRs!

--

Olly

[Kevin Bacon 5]

My VR temp rarely ever moves off 85/90 (water)..... except after prolonged spells of full throttle through the gears.

 

But yeah, took me an hour to do.....so maybe budget for 2 to 3 then if you've not done one before. You just need to take the top nut of the front engine mount, remove the airbox etc, jack it up so that the pump pulley is just proud of the inner wing, crack the bolts out as described above, slacken belt, remove pulley, pull out old pump....refitting is reverse blah blah....

[Funkster 0]

Excellent - I'll have a go at that if GSF have a pump in stock. Am I likely to break anything else in the process? I'll put a new belt on as the existing one looks a bit tired.

 

Thanks,

--

Olly

[fla 9]

Mmm, seems it doesnt like high temps. Got to 112C oil yesterday in traffic (very stop go) and after pulling in to a petrol station, of all places, it didnt want to start as I moved in after the pump space cleared. :oops: Left it for a few mins and it started up nicely. Having said that, it then tried to cut out about 3 times on the 2 mile drive back home, and the temp gradually came down to a more normal 104C. Is this just one of those VR6 things? The mocal is on the way so I just need to install it (guide would help chaps!), so maybe this will solve the problem.

[Kevin Bacon 5]

Your idle valve might have got a bit sticky due to the mega heat it absorbs off the exhaust manifold from sitting in traffic so long....mine's a bit like that at times too mate.

 

The mocal installed in front of the rad is good for traffic jams as the rad fans cool that down aswell as the rad....but you've got aircon, so unlucky, no room for the mocal. It'll have to go down in the inner arch where the G60 intercooler normally lives.

[fla 9]

It'll have to go down in the inner arch where the G60 intercooler normally lives

So that means no cooling fan assistance to the mocal? Any tips on the install? I'll post some pics of teh bits I have when they arrive so maybe someone can tell me what else I need and how to install. Cant see it will be too complex - remove the existing cooler and plumb this one in with the new hoses (of course not that simple!). How to mount it would be an interesting question.

[Kevin Bacon 5]

Yeah it's easy, providing you're sent the correct sandwich plate (custom made) and hoses etc.

 

It *might* sit in front of the aircon rad mate, I've never tried (anyone else with aircon?) but it was tight enough on my non air conned C. If Mocal do a slightly longer and thinner cooler, that could be your answer.

 

If it does need to go in the inner arch, you can run an auxillary pacet fan off the rad circuit to cool it down in stationery traffic.

[Walesy 0]

is this the right sandwich plate?

[fla 9]

Got it off ebay so i guess it *may* not have all the necessary bits. BTW, whats the best way to clean the rad fins - a blast with a pressure washer maybe? Just a thought on the cooling effect of the fans, they might not be able to draw enough air through the plates. One section is obscured by the aircon rad anyway so that wont get cleaned at all, unless I remove it.

[Funkster 0]

You just need to take the top nut of the front engine mount, remove the airbox etc

 

fwiw, I found that I had to take the bolt out of the rear engine mount as otherwise the crank pulley hit the chassis rail and prevented the engine coming up enough to get the pump or pulley off. Still managed to do it in about 3 hours, and I took photos so I'll put 'em up here sometime.

 

Doesn't seem to have made any difference though, didn't drop below 90 quickly after moving off, although it did come down after a while. Also got oil up to 114 while just tooling around the back lanes, and it's cool out tonight.

 

Anyone had any bad experiences with aftermarket radiators?

--

Olly

[Dr Forinor 0]

My water temp usually sits between 95-105, hardly ever goes above this, but hardly ever goes below 95 once it's warmed up. Is this normal?

 

Sorry if it's a stupid question but it's my first time ever owning a "real" car and it being a special one, I'm very paranoid.

[Walesy 0]

sounds absolutely bang on to me mate! :D

[Dr Forinor 0]

Excellent, thanks man :)