vr6 running hot

[fla 9]

Ok, got 114C with some town driving yesterday evening. Due to the specific heat capacity of the oil it took about 15 minutes of a steady run on the motorway to drop down to around 100C. Something's not quite right, but i cant work out what, suggestions welcomed, Thanks.

[MonkeyVR6 0]

As mentioned already, VW's G12+ coolant is generally what we use, but it's not law. What is of concern is your 50/50 mix. Ideally it should be around 75/35 water to coolant, but no higher than 60/40. Water's ability to absorb heat reduces the more coolant you mix into it.

 

Dude, how many containers of VW's G12++ coolant do I need to buy for a flush/refill?

[Kevin Bacon 5]

The coolant capacity is around 10 litres IIRC, so I would use 2 and half bottles of G12. Maybe 2 if the radiator, matrix and engine aren't drained completely.

[MonkeyVR6 0]

Cheers dude, I'm going to get some tomorrow. Is it easy enough to get the pipe off the bottom of the raidiator?

[Kevin Bacon 5]

Fla, I suspect your main water pump could be on it's way out.

 

I had exactly the same symptoms. The main pump 'looked' OK and was a GSF metal bladed one. But I replaced it anyway with a plastic bladed one ("Airtek" or something IIRC, also from GSF) and temps fell right down. Water temp sits at 85-88 on a cruise and oil never goes over 98, averages 96, even this time of year. Also takes ages to get up to the 95 deg fan switch on speed. My previous temps weren't far off yours.

 

What was interesting was the sheer quantity of brassy coloured metal particles stuck to the magentic drive system of the electric secondary pump, the same colour as the blades on the metal GSF pump funnily enough. Brass isn't magnetic afaik?, which can only mean the grade of metal the GSF metal pump uses is pretty poor. In fact when I asked for a metal bladed pump, they didn't have any, so wonder if they've stopped selling them?

 

Anyway, for the price of a new pump (less than 30 quid) it's worth a go. Make sure also the radiator isn't partially blocked with silt and rust as that makes HUGE difference to running temps.

[Kevin Bacon 5]

Cheers dude, I'm going to get some tomorrow. Is it easy enough to get the pipe off the bottom of the raidiator?

 

No worries. Bottom hose is a bar steward if it's still got the original spring clamp on it, might be easier to take the battery out as it's usually on top of where you need to get to.

[_leon_ 0]

Hasan remember in traffic the external cooler gets no air flow - so temps can continually rise until you get moving again. In traffic (think M25 jam) I don't usually see more than 104 though, reducing to 96ish when going again. Water temps when on the move staying roughly around 85-90, only going above when stuck in the M25 jams ;) And thats on a new VAG water pump, 16row mocal cooler (half covered - keep forgetting to remove cover!) and recent oil change.

[Kevin Bacon 5]

Agreed, but he's getting some pretty major heatsoaking by the sounds of it, which is usually a sign of a weak cooling system. As you say, a healthy setup with a mocal receiving no air flow shouldn't climb THAT high.

 

Taking 15 minutes to disperse the heat once on the move again further points to that, but I could be wrong :D

[fla 9]

Leon, Kev, thanks for that. Is it worth using any radiator flush solution to clean out the cooling system - i was thinking of removing the stat, opening teh drain valve on the crackpipe and running fresh water through the system until it ran clear, would take perhaps 4-5 minutes. If this method is okay, should it be supplemented with a rad flush additive.

 

Kev do you think that the oil flow to the mocal is ok? Just in case, what would be the best way to check it?

[_leon_ 0]

No idea about the flush additive, though flushing through can't be a bad thing and relatively easy to do. As for the oil flow - changing the pipes is a simple and cheap job, though I'm sure Kev had a blockage and he replaced the cooler unit too. If you find a way to test that the cooler is not blocked then I'd just change the pipes over. Of course Hasan replacing everything with a 24v unit would be the alternative approach ;)

[Kevin Bacon 5]

I did replace the Mocal, but it was needless in the end as it turned out to be the main water pump as mentioned ealier! It was only 2 years old, so assumed it couldn't be that. But that'll teach me for using GSF cheap schitt.

 

Hasan, VAG sell a big tub of bright orange stuff which is coolant flush designed to remove rust and sediment. You drain the G12 out, stick that in with a bit of water and then run the engine for a bit. I reckon the oil flow to your Mocal is OK, although it's hard to say without seeing it.

[Neil VR6 0]

Don't know about you but I've always been wary about using any kind of flush in my engine or coolant. I can just see bits of sediment being loosened and ending up in some narrow galley in the engine where coolant or lubrication is critical

[Kevin Bacon 5]

That doesn't happen in a VR in a reasonably well looked after car. It doesn't have especially fine galleries in the head or block.

The only coolant related issue that does cause permanent damage (other than the usual things) to a VR6 is insufficient quantities of G12 additive, which can pit the head very deeply.

 

I have 100% faith in the chemicals VAG use. They wouldn't use them if they didn't work. The stuff they get is seriously next level compared to what you get in Halfords.

[fla 9]

OK thanks for that. I'll pick up a few bits from VAG this weekend hopefully and flush it all through. Hopefully should put my mind at rest....

[_leon_ 0]

Hasan - did you try flushing the coolant?

[fla 9]

didnt get round to it this weekend, hopefully next one - i'll let you know. Having said that, we had a good ol' blast yesterday and the max oil was 110, coming down quite quickly to 104. Water was at about 95 never higher and also didint take too long to come back to around 80ish. Confusing, but after its all flushed and the pump changed it'll hopefully be ok. How much are waterpumps at VW?

[_leon_ 0]

around 40 quid i think - not much. i didnt have to give my old one in either.

[fla 9]

mmm, just called my local dealer and he said £75 plus a £25 refund when the old one comes back, making it £50. Apparently they are only on exchange?

[_leon_ 0]

Chiswick didn't insist on exchange. Ruislip branch is awful in case that's where you contacted. To say I've experienced the worst service in the last 10years at Ruislip is a complete understatement - utterly useless.

[fla 9]

Bit of feedback here - just came back from a good ol' run. Water went up to around 94 (doesnt normally go higher), oil went up to 110 and by the time i got back it was at 104. It was raining pretty much the whole trip so you would expect some further coolig from that. Anyway, opening the bonnet and tried to touch the water rad - very hot, annd the fans were on. Oil cooler - now thats different. V slightly warm, albeit access was somewhat limited. But there was no major heat coming from it, and with an idicateed oil temp of 104 i would ahve thought there would be loads. I had thought of spraying it with water, but it was too drizzly to do that. My conclusion is no flow to the cooler, either by way of a blockage or the sandwish plate not opening. Any other thoughts, or how can i verify this without taking it all apart?

 

Tried a few dealers for the rad flush and no-one has it. The Holts one looks okay, might just use that, unless someone suggests otherwise.

[fla 9]

Kev? You dont still have the other mocal to see if mine is actually faulty?

[awright182 0]

No disrespect but you're all getting carried away. Before the cam chains were done he had a car that worked. Dodgy water pumps and the like are all a distraction. It would have been dodgy too before the cam chains.

 

If there is really a difference it must be as a result of the work carried out.

 

Andy

[fla 9]

Just a short trip today, oil only got up to 70, *but* i reached down to check both the hoses to the cooler and they were both warm, suggesting that oil was going to it. In fact, taking the grille off, the cooler was also quite warm, not hot. But at 70C? I thought the thermo plate opens at 80C? I'll try and check the pipes once it gets to a good temp next time.

[_leon_ 0]

Just a short trip today, oil only got up to 70, *but* i reached down to check both the hoses to the cooler and they were both warm, suggesting that oil was going to it. In fact, taking the grille off, the cooler was also quite warm, not hot. But at 70C? I thought the thermo plate opens at 80C? I'll try and check the pipes once it gets to a good temp next time.

 

sounds like theyre warm from engine heat - rather than flowing oil

 

are you 100% set on going 24v Hasan?

[Toad 0]

Where did the mocal come from?

 

A few people have mentioned that they have had Mocals which have made no difference to oil temps to me in the past.