Coolant/oil temp issues - ALL SORTED!

[gradeAfailure 0]

Right, here's what happened:

 

Prior to last weekend, my coolant temp would usually sit at about 75-80 during normal driving, and the oil temp at around 112-114. In traffic, however, the coolant would go up to about 105, and the oil once got up to 140! So, last weekend, I decided to drain the coolant, flush the system, and replace the thermostat and fan thermoswitch; which I duly did. I have to confess to not using G12+ (like I should have) but Halfords antifreeze, as I figured it's be ok as long as I fully flushed the system - which I did.

 

Anyways, on the journey up to Inters on Sun, at a steady 80mph, my coolant was now reading 90-95, and the oil temp was 128-130! WTF?! After speaking to a couple of people at Inters, I decided to replace the thermostat again, this time with a VW one... Which I did yesterday... I actually made a point of checking the VW stat against the removed new one in a pan of water, and the VW one opened more, and sooner than the 3rd party stat - all well and good thought I...

 

How wrong I was.

 

On the way to No-Rice tonight @ 80mph - coolant temp:90deg, oil temp:132deg! What the hell is going on?! The thing is, when driving at lower speeds, the coolant temp stays the same, but the oil temp drops to around 120... Whe I got home, I checked the rad hoses - the top hose was too hot to touch, but the bottom one was just nicely warm...

 

Is it still the thermostat? Will flushing the system (again) and putting in G12+ really make that much of a difference? Should I run it for a day of so with no stat at all, just to see if the temps come down?

 

Sorry for the essay, but I though it best to give all the facts in the first post! :oops:

 

This is really peeing me off, especially as I have to take the PS pump bracket off to get to the stat and it's a right pain having to keep draining the coolant and swapping stats over... And no, I don't still have the original stat, stupid me...

 

Help me before I cry!

 

Cheers (from someone just wanting his car to behave...)

[Walesy 0]

cant offer help sorry bud....but my 8v also runs hotter now since changing thermostat and thermoswitch....my oil temp seems to be fine (( although ive not done any long runs )) but tthe coolant sits at around 100 where it used to sit at 90......

 

Im thinking of putting a Neuspeed thermo and switch in.....(( the cooler running ones)) ...have you thought if that.?

[gradeAfailure 0]

Yeah, I did think of that, but I'd rather get back to where I was with the temps, and then work from there as there's obviously something wrong...

 

Anyone else got any ideas?!

[randal 0]

Would a block in the coolant system start giving you problems like this?

 

Also, I take it yer fan kicks in when things start getting really toasty?

 

Sounds like a real pain in the wotsit mate, hope you get it sorted soon.

[dr_mat 0]

Flush the coolant again and put G12+ in there and see where you get to. Your 'stat should open at 80 degrees, so normal water temp should be 80.

[gradeAfailure 0]

Yeah, the fan kicks in during normal town driving, which is both reassuring and worrying at the same time!

 

I fully flushed the system out before refilling so I'm fairly sure there isn't a blockage, but you never know...

 

Yeah, it is a pain 'cause I now don't really want to drive more than ten miles at a time which doesn't leave me many options!

[mrbeige 0]

I changed my thermostat when replacing the water pump, and since then water temp has been hotter than it was before. I used VW thermostat and G12+, so I have a similar issue. Why would it run hotter? I can't offer any help, but safe to say that you may have a air lock in the system. I'd suggest the same as dr_mat, flush the system and get some G12+ in there and see what happens.

[Garry 0]

Make sure you don't have an airlock in your water system.

[Garry 0]

Make sure you don't have an airlock in your water system.

[gradeAfailure 0]

Yeah - I did fill the system from the expansion tank not the top hose, but it was filled very slowly and the hoses were squeezed as I did so to try and prevent an airlock, but I suppose anything's possible... I have the afternoon off tomorrow so am going to be getting covered in coolant again!

 

All suggestions welcome as I'll try anything! It just confuses me that the coolant isn't getting into the rad hence the lack of cooling at high speed, yet the fan thermoswitch is switching the fan on...

[dinkus 10]

Firstly, I'm no kind of expert here, but just taking some semi-logical guesses

 

If the water isn't getting through the radiator then it sounds like one of three things...

 

you have an air lock

you have a blockage

your water pump is dead

 

Surely if you did have an airlock, it would bubble to the top of the system, i.e. the top rad hose? So if the top rad hose is boiling hot then that would imply that there's water in it, and thus a blockage somewhere else?

 

A blockage is possible, but I've no idea how you find that!

 

Are you sure that the water pump is still working ok?

[gradeAfailure 0]

Are you sure that the water pump is still working ok?

 

TBH, no, I'm not anymore! Though it seems pretty random, not to mention an amazing coincidence, that it would fail at the exact same time that I do a coolant change and replace the stat...!

 

Anyone know the best way to check if the water pump's working?

[NickVR6 0]

Hi mate, sorry to here of your probs. I had the same on my VR and found my self scratching my head saying wtf.

 

I replaced my stat twice and it ran hotter on the water temp than before hand. I was worried about my oil temp most. Flushed it twice and it ended up being an airlock in the hose that runs to the heater matrix. I replaced the presure cap first no joy, then did the hose, still some probs. but after filling from the top rad hose everythings been hunkuss mcdorey.

 

Try filling it back up from there, no need to drain it again. its messy i know but it worked for me (thanks to Dr Matt's advice). My garage still wont beleive that was causing the problem, but it was!!

 

N

[NickVR6 0]

Run the car up to warm with pres cap off and see if its pumping through the small hose into the header.

[gradeAfailure 0]

Fantastic, have had that opinion on msn from a couple of others too, so Sat will be a full drain, flush, new auxilliary belts (just to make sure), and refill with G12+ (I've learned my lesson) from the top hose. Though on mine, the top rad hose goes to the engine block almost horizontally, so I don't know how I'd go about filling up from there? Any suggestions?

[A20 LEE 0]

Mine ran hot after a coolant service too. Oil 124° on the motorway, started to worry, however on the return journey was back to normal 112-118 as a steady 80ish* cough.

[NickVR6 0]

It was a be-hat*h on mine too. i just bent the pipe virtically and brimmed it then stuffed it on as quick as i could! Lost loads but it still did the trick.

Made sure i polished all the colant off the paintwork after too!!

 

Not sure what yours looks like though. Im no expert by the way, just letting you no what mine did. I thought something really bad was going on like big blockage or failed pump, and my garage gave up after 3 visits but it really did turn out to be that simple!

[gradeAfailure 0]

Actually, I do have a thin hose that runs between the junction on the block where the top rad hose goes to and the top of the header tank - anyone know if you can pop this off at the header and fill from there to avoid airlocks?

[Toad 0]

when I first got my valver, I changed the coolant, can't remember why now, but i think it's fair to say i've put about 50l through it in 6 months!!! anyway, I re filled the beast, but it kept blowing water out and overheating, it turned out a lump of cack had blocked the hole in the top of the rad which the breather pipe (the little one which runs to the top of the header tank) attaches to. when you run the car up, you should be able to see coolant and air bubbles moving from the rad to the header tank through the end of the plastic fitting on the tank. if you don't try getting the pipe off and poking the radiator fittting with a paper clip-its a pretty small hole. as the bishop said to the actress.

[gradeAfailure 0]

:mad::mad::mad::mad::mad::mad::mad::mad::mad::mad:

 

I don't know any expletives strong enough for how I feel right now...

 

Drained the cooling system - again.

Flushed the system (rad, block, and matrix separately) - again.

Checked thermostat in pan of water - again.

Fitted it all back together and refilled the coolant (G12+ this time) - again.

 

Filled the oil up to the max mark as well...

 

Let her idle til she came up to temp - 85deg coolant/100deg oil

 

Went for a drive....

 

AAAAAAAAAAAAAAAARRRRRRRRRRRRGGGGGGGHHHHHHHHHHHHH!

 

Exactly as it was before! 90deg constand coolant temp, when it was 80 before I started all this, and 128deg oil temp, when it was 118 before...

 

What the hell is going on?! Mind you, when I got back and turned off the engine, at least this time the bottom rad hose was nearly as hot as the top hose. No airlocks either, as I'm getting good hot air from the heater. And the cooling fans Stage1 came on at 93deg coolant just like they should...

 

Anyone want to buy a Passat? Think I saw a nice cheap Y-reg Polo for sale locally for £200...

[Walesy 0]

its weird ...cos since having my head gasket done about 3k ago ive had nearly exactly the same probs........prior to the thermo change i was getting a steady 90deg water temp and around 96-106 oil temp....never really seeing any different....but now it sits on just under 100 deg and sometimes the oil goes to 112!......ive changed the thermo 3 times aswell....my mechanic reckons its reading hotter than it actually is.....but i dont...it seems hotter than before..........

 

not much help...but if you find a solution...let me know dude!......

 

I was gonna try the neuspeed duberries?

[Supercharged 2]

gradeAfailure, are you sure the water pump is working??

[gradeAfailure 0]

Pretty damn sure - it's not ever made any untoward noises, and the hot coolant seems to be pretty evenly distributed through the engine bay - the fan starts blowing out warm air after about three mins or so... Having said that, is there any sure fire way of checking? Surely if it was dead then it's be the coolant temp that was waaay to high, not the oil temp?

[Walesy 0]

Surely if it was dead then it's be the coolant temp that was waaay to high

 

yeah..surly the temp would go through the roof...and get the light flashing?

[Henny 0]

Sounds to me like your oil heat exchanger is blocked internally... The water temps are fine, it's only your oil temps that are getting a bit silly... Change the oil cooler (they're about £30 from GSF / ECP ) and change the oil and filter too (it's not good to get it that hot) and see if that helps... 8)