Coolant and Oil temps vitually equal!!!

[colinstubbs 0]

My 1.8 16v has just started hitting around 110degs on both Oil and Coolant on the 18 mile trip to work.

 

When this happens the coolant temp lags oil temp by 10 degs as per normal but the coolant temp gradually catches up with the oil equally it at about 90deg.

 

The blower will initially blow hot but this stops.

 

The rad hoses (samco) are pressurised very firmly but there's no venting from the expansion tank cap - on switch off you can hear bubbling in the top rad hose/coolant system and pressure gradually disipates with the fluid level in the expansion tank falling accordingly.

 

Once the hoses aren't pressurised hard i can squeeze them and force the last of the air(?) in around the system and the blower will have hot air again.

 

It seems to me that air/gas is getting in the coolant system which leads me to fear the dreaded Head Gasket failure, although there is no smell of exhaust in the expansion tank.

 

Is this all it could be or is there any other possiblity I can look/hope for? I'm not getting my hopes UP mind! :(

Edited May 14, 2011 by colinstubbs

[dannyboy 0]

is your whole radiator getting hot? sounds like your thermostat has failed closed or coolant pump is busted.or maybe head gasket as worst case.

 

feel the bottom of the rad,it should get very hot but dont be fooled into thinking that the thermostat works.only putting new one in(might as well since you have old one out and theyre not expensive) will give you piece of mind

 

Does the fan kick in? usually good indicator if thermostat has opened.

 

Failed head gasket is ususally dectected better when cold as it idle rough on startup due to coolant escaping into cyllinder and mayo on the oil cap

[colinstubbs 0]

Cheers for the reply dannyboy The bottom rad hose is hot, the fan kicks in (what temp is that s'posed to happen i can't remember?)

 

No mayo, idles perfectly apart from the odd drop from 950rpm to 800 which quickly recovers.....

 

It's the bubbling in the rad hoses that concerns me, it's causing an airlock in the matrix that stops the heater blowing hot air and the only way I can see that happening is blown gasket.

 

It's not like I have an external coolant leak either.

Edited May 15, 2011 by colinstubbs

[Supercharged 2]

It will be the fan switch ion the rad - the first stage has failed.

[colinstubbs 0]

Cheers for that Supercharged - I may even have one of those kicking about that I bought needlessly a number of years back!!

 

I'll report back whatever :)

[Yandards 0]

Cheers for that Supercharged - I may even have one of those kicking about that I bought needlessly a number of years back!!

 

I'll report back whatever :)

 

Bit of a waste of time though.

 

Your car does not need the rad fan until in slow traffic or stopped - driving forwards at 30mph will force cooling air over the radiator and ensure that the radiator does its job.

 

I would suspect water pump failure instead, a lack of coolant flow will give you the symptoms you describe and the boiling of the coolant in the system will generate the air pockets you are getting.

 

So how many miles has the car done and is it still the original coolant pump? If the miles are above 100k and you are still on the original pump then it will most likely need replacing as the impeller wears away over time, easy enough to change although a little messy. I would also get a new thermostat and a new thermostat housing whilst you are there as it is likely that the original plastic housing will crumble and the original stat may now be fecked thanks to the overheating.

 

Hope that helps!

[colinstubbs 0]

Not really what i wanted to hear Yan! (Better than a gasket though!)

 

It had a new water pump, stat and housing about a year or so ago because the pump started leaking, engine's on 207k now. Can't remember if it was a genuine one or not, I think it was due to the probs mentioned on here about pattern ones.

 

I've also checked the rad vent pipe to the expansion tank is clear and the pump seems to be pumping fluid around ok as it squirts into the tank as I rev the engine? Is there anything to check on the pump if I take it off to look at it other than the vanes are still there and the bearing isn't fooked?

[boost monkey 0]

Sounds like what happened to my C when the stupid clutched pulley let go. It would slowly creep up in temp, both oil and coolant, and then the expansion tank would whistle like a kettle.

 

Not sure if there's much to check on the pump, IIRC a genuine one is about £20 so not much hassle but I could be wrong on price. I'm going to swap the plum's one onto my golf very soon as it's only done about 100 miles.

[dannyboy 0]

did the older models get plastic ones? never seen them,ive only ever got metal ones.beware cheap ones,bearings are not brillant on them and seals leak destroying the bearing very quick. Buy cheap,buy twice

 

Sound silly but is your radiator matrix clean?

[Yandards 0]

Humn.

 

If you have had a new pump a year ago and it continues to squirt into the header tank then it's not likely to be the pump. :/

 

Next thing to look at as Danny Boy suggests above is a blockage in the radiator matrix causing the overpressure, again is this an original item or a newer replacment part?

[colinstubbs 0]

it's a newer pattern part, Having done a bit of a search on herei'm thinking that the fan switch is probably an issue as it don't seem to come on til 105-110C.

 

So at the mo i'm thinking change the switch anyhow as i have one and reverse flush the rad....

 

better get some more coolant then eh??!!

[colinstubbs 0]

Flushed out rad and changed the switch. Ran it up and the thermostat failed to open. I'm guessing the other times the bottom hose was hot was purely from conduction over the 30 mile drive to/from work or the heat has screwed the Stat :(

[colinstubbs 0]

Got a new stat, housing to be on the safe side and seal coming. That'll teach me to try and diagnose a coolant issue without starting with the basics......letting the fooker cool down!

 

Tw@t! :)

[colinstubbs 0]

great changed coolant thermostat and oil while i was at it, bottom hose stays cold and i've fitted brand geniune VW 'stat and tested it opened before fitting. Gonna have to try and see if the is a blockage somewhere, the rad seemed fine, went in the top and came out the bottom and vice versa.

 

I just can't see why the bottom hose is not warming up, the fan switch eventually comes on even driving and of course on turning off.

 

I'm gonna go through all the hoses and engine block holes and squirt them all with water. Something is amiss, i'll also se if i can scrounge some 22mm copper pipe from a plumber up the road and delete the matrix bypass valves. Not getting any hot air either, although i was to start with.....

[colinstubbs 0]

No apparent blockage, thinking it must be the pump, IIRC I'd bought and fitted a pattern one before reading on here it's a sh!te idea :(

Into work today and stopped once it got to 74c on the gauge to check under bonnet and it was boiling in the top hose. Just hope i can get it home ok. Of course i'm off this Monday but it's a fecking BH so no parts til Tuesday, although the chap did see if he could have got it in today but just a tad too late.

 

VW waterpump £49.80 after the surcharge just for the record.

[Yandards 0]

Heater matrix bypass if bust wont help but it is not the source of your problem.

 

Sounds like either a stat failure or a pump failure caused the initial fault and it has then spread to the other component.

 

IIRC the impeller on the pump is just a plastic one that is an interference fit onto the water pump drive so it seems more likely that this is no longer tight on the pulley shaft and therefore not moving any water around the system.

 

Be interesting to see what the end results is!

[colinstubbs 0]

It seems to have got worse Yan, had to pull over on the way home. To compound my misery I left keys in the ignition and the car locked itself, it looked like rain and my phone was nearly dead! My wife came to the rescue with spare keys, I had coolant onboard. New pump coming Tuesday.

[dannyboy 0]

If you have a plastic impeller waterpump i 100% guarantee its that cause the 1.8t's had same probs with overheating. As yands said the plastic impeller is pressed on the driven shaft and over time it rounds off and becomes loose on the shaft and doesnt circulite the coolant.

 

If its cooling ok at idle but starts overheating when driving,its the pump.

 

I feel for you colin,i had to sit at the service area at the dartford tunnel for 5 hours when my aircon pump seized on my g60.After a 11 hour drive from germany thats not what you want! Lol

[colinstubbs 0]

IIRC it's a pattern pump with a metal impeller, I hope this is the problem, I may get round to whipping off today so i'll update if I do - if not it'll be tomorrow. Kinda dreading getting it off and finding nothing wrong with it :(

[colinstubbs 0]

Got a sheared pump attachment bolt to sort out now but at least the pump impeller is loose and crap so that should be the issues solved!!

 

Fingers crossed eh?

[dannyboy 0]

Did you round off the allen key bolt? what was it in the end?

[colinstubbs 0]

I've removed the old pump and the impellor is loose so that is probably my overheating issue, unfortunately one of the attachment bolts is sheared so i'm looking at drilling that out tomorrow and re-tapping or trying some easi-outs, not sure if easi-outs will work well in a cast iron block???

 

Any preferences in that department??

[Yandards 0]

I've removed the old pump and the impellor is loose so that is probably my overheating issue, unfortunately one of the attachment bolts is sheared so i'm looking at drilling that out tomorrow and re-tapping or trying some easi-outs, not sure if easi-outs will work well in a cast iron block???

 

Any preferences in that department??

 

Yep the impellor should not spin on the shaft so there is your fault.

 

As for sheared bolt removal, is it flush/lower than the block or have you got some shank showing? I would always go for the path of least destruction in terms of removal; use loads of penetrating oil, then pump for the easy outs, you will need a decent size hole and try to fit the biggest easy out you can in there. Then whilst turning the easy out tap the back of the adjustable spanner (use that to grip the easy out) with a hammer to provide some impact shock to the turning force.

[colinstubbs 0]

Been awhile! I got the pump changed ok and all the ancillaries put back on and now it only seems to get to about 85C on the 18 mile drive to work, not really worried by that to be honest (although if the gauge is reading a bit low......how high had it really got before!!!???)

 

There is the small issue of grounding out reversing onto my drive at 2330hrs tuesday evening and rupturing the pressure fuel line from the filter forward but the new line should be ready to collect today - although I've been advised it's now an obsolete item and that's the last one in the UK at the mo, I'll try and get more info when I collect it.

 

I'd be lying if I didn't admit the a 'head in the hands' moment when I realised what I'd just done LOL

 

Temp repair on the fuel line (fuel line sleeving the break with two jubilee clips) seems top work a treat - no major rush to replace the buggered one then!! Less stress at the mo!! hurrah!

[boost monkey 0]

....until you ground it out again? How low is your car / steep is your drive?