Rapid overheating

[Sumpy467]

Hi all, anyone suggest anything for this-

Had a long journey back home today, all gong well for 200miles then I notice the temp gauge up at 90. Its never gone passed 90 before and this by itself not a problem, but a bit odd as i'm doing motorway speed and its below 4 deg outside.

Then i get the traction light flash on just for a split second, then a loss in power (will maintain 2000revs but won't accel) then all fine.

Couple of minutes later, no accel again then fine again. Does this 3 times.
Then, no accel, temp gauge goes full scale high in a split second and 'coolant' warning comes up on dash. So i switch engine off, hazards on etc.

Pop the bonnet expecting to see massive coolant leak, but nothing. No steam, no puddle. All appears fine. Get back in and switch ignition on, self test displays 'OK' so I start the engine, still OK, temp back down to 90 now. So I have another look with engine running, all appears fine.

So i elect to drive it , atleast off hard shoulder someone safer. Soon as i get over 1200revs temp goes full scale, coolant displayed on dash as before. Pull over again, have another look, went to unscrew the coolant cap as it appeared full/max, got half turn on it then felt it bubbling, so give it a danm good leaving alone! At this point I green flaged it home!

I'm thinking its the thermostat stuck closed causing the overheating and the ECU going wibble and switching to protect mode causing the loss in power.

Anyone got any suggestions/ experience of this?

BTW. its the 2.5TD auto, covered over 200k miles, timing belt and water pump done 10k ago.

Cheers.

[SWARCUP]

it does sound like a thermostat or possibly the new watert pump has failed

[RickT]

Sounds like the water pump has failed..

To test it.. remove the coolant cap, and start engine when cold, watch the coolant leve, it should "pulse" up and down as the water pump is moving the coolant around the engine, (give it a few gentle rev's too.)

If the coolant is not moving, then more than likely its the water pump..

Was the water pump changed when the cam belt was done? (if done) if its failed within 12 months and is an OEM part supplied by Audi fitted by them or a pro garage, (VAT reg) you may be able to get them to replace the pump picking up the costs.

Rick

[Sumpy467]

Had it checked today, was going to be a sniff test of the coolant. But engine doesn't want to play, looks like its partially siezed on the right bank. Not good cam belt stretched from the extra strain, and stinking!

New water pump was fitted with the belts, if it is to blame then there maybe some comeback on it from the manufacturer. Maybe.

Replacement donk looks like the best part of 2 grand

[scooby_d0o]

I did my engine just over 12months ago, and i could find replacements for about £1200 (same engine 2.5tdi)- plus then fitting (unless you do it yourself) but i believe you need the instrument clusted of the donor car - or you deffo need the engine coding to your car - Shark or someone may be able to help you with this aspect - but its not as easy as just swapping the engines over - in the end i opted to repair mine - spent just under £2k (i must have had one of the last orders with VAG parts) replaced bent conrods, bigends, gaskets, seals, water pump, pistons -rebuilt the engine - took me 2months in my spare time - glad i did it now rather than take on an engine with no history, worrying at the time spending all that money and not knowing for sure it would be ok.

Deffo sounds like the pump has failed or whoever did the work did something wrong..have you spoke to them about it?

[Sumpy467]

cheers scooby_d0o

can you tell me where you got your components from? -pistons, valves etc.

I think i'm going to stick it in my garage and progress it slow time (got the pleasure of my old chaps audi 80 sport b3 to use). start by stripping heads off and have a look at the mess inside and go from there.

any advice/tips on stripping would be greatly appreciated!

[scooby_d0o]

I bought everything from a company called VAG parts (sure thats what it was called) but they've ceased trading now though- they were probs about 25% cheaper on genuine audi parts as they bought them in from Germany (when you got alot of Euro for your Pound) but as soon as the Euro and Pound got closer to parity they could not make a profit on parts so closed up.

Tips wise - It seems really daunting when you start, but if you take your time, make notes and take pics you'll plod on through it. If you can, take the engine out of the car, i found that to be the biggest benifit - made working on it loads easier - i was lucky though - im an engineer for a haulage distribution and storage company, so all my tools were in work, and i used one of our HGV maintenece bays - also called in a few favours, got hold of a 2poster ramp so i could get the car off the floor. another must - get one of the pipe clamp removal tools (water pipes, fuel lines etc) i scraped my knuckles so many times undoing these. and take your time undoing the electrical connectors - they break really easily.
the bottom end of the 2.5 engine is a mare - 2 sumps - also the oil pump chain is in there - i had a pain here.
Also dont change ur glow plugs, i did mine while engine was out as i thought it would be easier - it wasnt - 1 snapped just after id put the heads back on (70 for a new gasket, 14 for bolts) i managed to drill it out though - i was very lucky.
1 last thing - buy the proper locking tools from VAG, nt the cr@p you see on ebay - i bought 2 kits from ebay - both of which did not have all required components even though they said 2.5tdi etc - ended up getting them from my local VW dealer - £80odd i think (cam locks, crank lock and fuel pump lock)

hope this helps you a bit - good luck

[Sumpy467]

Many thanks scooby_d0o

I've managed to get hold of a used donk from the scrapper, complete engine done 80k miles. Quite happy with it as it comes complete with diesel pump, injectors, turbo etc Mine having done over 200k were a bit worse for ware.

I was quoted 500 quid for fitting, but it seems that doesn't include new belts, tensioners, water pump etc Would be daft not to fit new bits. I need to phone them direct (been done through a mate) and get an exact quote, but I'm not very happy spending any more than that on fitting. Still mulling over wheather to try fitting myself, haven't really got the time -or the tools!

Anyone know of a good independent fitter in or around Peterborough that specialises in VAG?

[Sumpy467]

Ok, so it’s been a few months in the garage.
Upon taking the front end off and having a look it turned out to be the water pump that had failed (all those that said that above- you are gods).

Unfortunately, the seized bearing stripped the cam belt and valves got very friendly with pistons.
The donor engine I had lined up didn’t materialise so I went for a diy remove, overhaul and fit. Many thanks to Scooby_Do0 for the advice, took loads of pictures, bagged and tagged everything, very time consuming but worth it.

Just finished popping it back in.

[Sumpy467]

Got engine back in, but can’t get it started for more than 5-10 secs. I knocked up the remote switch for the tank pump. Clamped off the supply hose (less than 1/3 fuel in tank to fill the baffle) then removed it and clamped the return lines and bleed it, then bleed it some more. Cranked it and bleed it again, cracked off the injector pipes. Each time fuel flows bubble free, but still won’t start.

I’ve done a scan:
01375-166 Valves for engine mount: stage 1
Sporadic- output does not sw. /short
00550-155 Start of injection regulation
Sporadic-implausible signal
00542-030 needle lift sensor
Static- open/short to positive

I put used injectors that had done less miles in on the rebuild, so put my old injector back into cylinder 3 and cleared the codes. Just 01375 returned, I gather this is the engine mountings? Not sure exactly what this means. Still won’t start.
Also, I have no throttle response, but this may be because the engine hasn’t reached idle so ecu doesn’t recognise throttle movement? Perhaps I’m barking up the wrong tree there?!

Anyone got any ideas?