coolant...thermostat...radiator?

Post by **GusBus** » 23 May 2007, 14:07

Have spent all morning searching for schtuff on here,and the OH has spent all morning getting oily under the bus.

Symptoms....driving home from Westport (Co. Mayo) to Co Tipperary last weekend and it was getting mighty hot.
Self-preservation kicked in so I turned the cab heater on full, and clicked the fan to its highest setting. Made little or no difference whatsoever, which surprised me, as this always worked on other old cars.
Stopped regularly to (a) allow it cool down, and (b) check/top up water...rarely needed any.
Had to drive the whole 4 hours journey at around 40mph...any higher and that needle shot to the far right. At around 40mpg it was only 3/4 of the way over, and that was as low as I could get it.
Was very tired after a weekend of camping and socialising, didn't occur to me to check the radiator.

Drove it to work yesterday....worse...anything over 30mph and it was heading to boiling point. Brain engaged when I got to work, and I put a hand on the radiator...stone cold, after a half hour journey involving lots of long hills, and consistently high temp guage readings. Checked water, still filled to top....but clearly very hot and smelly engine.

Aha....thermostat...I presumed.

Bought shiny new thermostat this morning, topped up and bled the system...running as hot as ever. In fact, even at idle the temp needle was 3/4 over.

So what is the next logical step?

The OH wants to drain the system competely and run a rad-flush through it? Is this the next logical step? And if so, he's asked me to ask you all how to fully drain the system....an idiotproof step-by-step guide (or link to same) would be very appreciated.

If the rad is fecked...he wants to know if the rad from a Nissan Cabstar pickup would fit? I said no, but he asked to ask anyway

Review of symptoms:

Running very hot
No water leaks
New thermostat fitted
Rad fan soundslike its working OK
System bled for airlocks.
Now rad is tepid in some areas (an improvement?), stone cold everywhere else, no warm/hot spots at all.
Still running very hot
Still no water leaks

Post by **GusBus** » 23 May 2007, 14:08

Oh...for what its worth, its 1Y engine (1.9D n/a) out of a '91 Vento, been in since March 07 with no problems.
Brand new water pump as of October last year.
Anything else you need to know?

Post by **kathyshack** » 23 May 2007, 14:25

Not an expert at all, but I'm sure I have read on here that it is not advisable to use a rad-flush, as i think it can end up blocking your radiator.. sure someone will be here shortly with better info, but i'd hold off using the rad-flush stuff just to be one the safe side.
kathy

Post by **GusBus** » 23 May 2007, 14:29

I read the same warnings, but with regard to Rad WELD?

Are you sure you mean Rad FLUSH?

Post by **toomanytoys** » 23 May 2007, 14:46

Are you sure the rad is bled? and the pump is actually ok.. sounds like coolant isnt getting round the system.. either from a blockage or lack of pumping..
the water level isnt moving? not blowing it out then?
Could it be that the temp sender/gauge is faulty?

if it was all ok and has suddenly started doing this, then I would suspect something has broken (pump) or blocked the system..

Post by **Westy.Club.Joker** » 23 May 2007, 17:13

Did you buy a genuine VW thermostat or a pattern one? Non-VW ones are notorious for causing the symptoms you`ve got.

Try VW thermostat first, then check that the pump is actually pumping water, check the hoses for heat by hand, and also where they connect to the radiator. Does the heater blow hot? Does sound like a flow problem, which can`t be many things, either pump, or thermostat stuck shut would be my bet.

Post by **GusBus** » 23 May 2007, 17:48

Hi guys

Thanks for replies.

We think the thermostat is fine...and in fact the old one was probably OK.

The OH is tending towards a blockage in the radiator.

We've no garden hose here, so trying a slow-motion flush trudging back and forth to a tap with jugs of water, and getting the occasional bit of black sludge coming out when the engine is running. So we are assuming there's a black sludge monster in the radiator.
Anyone come across this black sludge before? What causes it? How do we flush out the radiator? At the moment we're pouring water in at the engine end, and the water pump is pushing it out of a hose we've taken off at the radiator end (bottom of the radiator) with just the occasional splurge of water out of the radiator itself...but we can't see how to physically flush the radiator itself without removing it. Are we being fik?

Post by **GusBus** » 24 May 2007, 09:25

Erm....any implications to using the radiator from a petrol T25 on a diesel T25...?

Post by **jason k** » 24 May 2007, 16:01

gus bus we had the exactly the same probs on my mates bus.his rad was blocked up too. we had a gsf rad but trust me , go to vw buy one of their thermostats, i know they are expensive but it will work.
gsf etc ones are useless and dont work i have been thru a few of em on my mates bus.

Post by **camper** » 24 May 2007, 16:34

Sure its not black oil lumps instead of sludge.Could be the oil cooler leaking ie the metal part with two small hoses between the oil filter and engine block.The coolent can loose presure in the oil cooler.Check the expansion cap is holding presure and as other members said use only VW parts if you replace.

Post by **Westy.Club.Joker** » 24 May 2007, 18:53

I believe petrol and diesel rads are actually the same part on the T25.