Thread: Viscous fan possibly not working properly

Ok, just been doing reading on signs of the head going, I am going to pick up a genuine reservoir tank cap today and rule that one out. But not getting a good feeling about this.....If you read the other post I have just started about losing performance in 4th, especially up hills, they may well be linked. No other signs at all, no white smoke, oil in coolant, but it is pressurising up more than it used to. Not losing coolant though....

It has 315k, but is a 2003 model which I believe has the steel dowels, are there any other tell-tale signs what it could be ?

Cheers,

Matt.

Originally Posted by surfingooner

.... are there any other tell-tale signs what it could be ?

Cheers,

Matt.

steel dowels? so Td5 then?

You say maybe over pressurising, but not loosing coolant.

Try this:
take reservoir cap off first then get engine up to temp.
Make sure reservoir is still pretty full and let it sit and idle for as long as you can and watch to see if coolant 'pumps' itself out of the top of the reservoir.
Also watch for something like a stream of air bubbles coming out of the reservoir tank too.

All signs that the engine is pressurising the coolant system via hot gas ... ie. head gasket type issue.

Is where the famous " tape a coke bottle to catch the overflow" trick works?

Originally Posted by AK83

steel dowels? so Td5 then?

You say maybe over pressurising, but not loosing coolant.

Try this:
take reservoir cap off first then get engine up to temp.
Make sure reservoir is still pretty full and let it sit and idle for as long as you can and watch to see if coolant 'pumps' itself out of the top of the reservoir.
Also watch for something like a stream of air bubbles coming out of the reservoir tank too.

All signs that the engine is pressurising the coolant system via hot gas ... ie. head gasket type issue.

Thanks and just completed the test, best part of an hour, let it idle and then from 82 degrees, held at 2,000 rpm until I got to 86 degrees.

I filled the reservoir just past the mark when put the new cap on, so it was a little over-full starting the test if anything. At 82 degrees, the reservoir was nearly to the top, but nothing over-flowing. When I revved to 86 degrees, the moment I let off, there was a small burp and splutter out, very small amount of fluid (see photo). After that it settled down again (see second photo).

I should add that it still has water in it since losing all my coolant during the camping trip, so not sure if replacing with coolant will have an effect also.
Overflow.jpg86 degrees.jpg

But after this, I am thinking the head is OK, what do you think ?

Originally Posted by surfingooner

Thanks and just completed the test, best part of an hour, let it idle and then from 82 degrees, held at 2,000 rpm until I got to 86 degrees.

I filled the reservoir just past the mark when put the new cap on, so it was a little over-full starting the test if anything. At 82 degrees, the reservoir was nearly to the top, but nothing over-flowing. When I revved to 86 degrees, the moment I let off, there was a small burp and splutter out, very small amount of fluid (see photo). After that it settled down again (see second photo).

I should add that it still has water in it since losing all my coolant during the camping trip, so not sure if replacing with coolant will have an effect also.
Overflow.jpg86 degrees.jpg

But after this, I am thinking the head is OK, what do you think ?

I would run the test again to be sure. Another good test is to get it up to operating temp and find a good hill to drive it fairly hard up, if it is a head gasket it will pressure the hoses significantly.
Nick

When I checked my HG I raised the expansion tank overflow pipe above the cap height, then topped up the tank nearly to the brim and above all return lines.
When running you will see big bubbles if it has a faulty gasket, I not sure small bubbles indicate much they could be from cavitation, the big ones are what you are looking for.

Originally Posted by surfingooner

....

I should add that it still has water in it since losing all my coolant during the camping trip, so not sure if replacing with coolant will have an effect also.
....

I've never had any car run hotter or cooler with or without 'coolant'.
So I'm going to say I doubt very much any heating up, or overheating issue will be due to the coolant strength.

I ran my Tdi for about 2 months or so with straight water whilst trying to sort some cooling issues, never ran hotter just due to straight water.
I also ran CEM flush stuff, and now run a Penrite coolant, and main running temp is where it's always been.

So if you're not loosing coolant, ie. confirmed coolant level remains the same, no slight drips .. then more than likely is going to be the viscous unit.
Annoyance of that is that the viscous and fan are a single unit on the TD5, so it seems that replacing a viscous is made more expensive(than say on a V8) for no good reason.

Like someone else mentioned too, have you bled the cooling system again to be 101% sure it's done properly.

I initially had trouble doing my Tdi properly proper(even tho I thought I had it), and had a scare moment on the drive to work one day. Pulled into a servo bled it again, half way to work, bleeding done.
Second time around I mucked it up again!(you'd think first time around you'd learn).
Then came across blacknights method of using a drink bottle in the reservoir filler neck, upside down, and bottom cut out to act like a funnel.
Did that a couple of times, but you get coolant 'everywhere'. so I bought a cheap cooling system pressure checker. Now I use that. Fill the reservoir pump it to 15psi, wait a little, undo the bleeder, watch flow, nip it up .. etc.
Do it all from cold too so no more hot high pressure washes on the arms/face/chest either now ...

ps. I actually didn't buy the coolant pressure tester for the job of bleeding cooling systems, dad smashed his little peugeot and it had cooling issues after that too. turned out it was coincidence. Pressure test kit was cheap off ebay for a bit over $80 .. so why not

With the accident, did the radiator get pushed into the fan?
If so, then I'd reckon 99.9% chance that the viscous is knackered now.

Do you run A/C? if so or if not, does it make any difference.
I'm sure the Td5 is similar to the V8 in this next bit, but at about 100 or so degrees, the AC condenser(thermo fan) fan will come on, whether you have the A/C on or not.
If you have the AC on at all, whilst you're driving and it's getting hotter .. have you checked the AC condenser(or thermo) fan to be working?
will be on with the AC on irrespective of engine temp. Just the side note that it comes on by itself if the coolant temp goes above about 100C too.

So when you say in your first post you can't hear the fan ..
Does this mean the thermo/condenser fan, or the loud whooshing noise of the viscous fan.

pps. if you ever need help to check stuff, let us know. Could have a bit of time to assist every now and then.

Many thanks Arthur, if Ok, I might try and get over and see you sometime, will PM. Yes the Viscous fan did touch the radiator in the crash, but was only a small dent and engine had only been running for 5 mins when it happened. Just driving around the campsite with daughter when a dog ran out. Sadly I have deleted the photo now, but was only a small dent on the radiator, but enough to cause a leak.

I haven't done a proper flush since, was waiting till I refill with coolant again. It would be great if I could get a second set of eyes on it, I am a bit out of my depth here.

Thank you.

Matt.