1.6td turbo question& overheating

Post by **camper** » 21 Oct 2006, 18:10

I have been having overheating problems with a M11 1.6td golf engine installed in the T25.Rad is cold when the water is boiling into expansion tank after a fast run.To date head gasket changed due to oil leak running out of the gasket.Oil cooler /expansion tank/thermostat replaced.Pipes checked for leaks.Expansion tank cap was replaced but was found faulty .The last episode was on friday when after a fast run 55/60 mph i had a a boil up with a cold rad that was when i found out i had a the faulty G.S.F replacement expansion tank cap.On that occasion i also noticed the turbo was noisy a metalic whirring this seems to coincide with the overheated engine .Regarding the overheating i still am not sure if its a cylinder head problem ie crack/leakage .The turbo noise i dont no if this is normal.

Post by **Westy.Club.Joker** » 21 Oct 2006, 20:03

If your rad is cold and the engine is boiling then it looks like a water feed problem. Could be the thermostat sticking shut, a blockage in the pipes or maybe a seriously clogged rad, or a mega air-lock in the rad ? Try opening the top bleed screw on the rad, bleeding method has been detailed on here before, as well as on the Brickyard.

Does your heater get warm? Are the front-to-back water pipes warm?

Metallic noise from turbo is not goo, usually means that the bearings are shot allowing the spindle and compressor/impellor wheels to float and hit the casing, causing the metallic noise. With the engine OFF if you get underneath and remove the inlet rubber from the turbo (looks like a cranked swan-neck rubber moulding) then you can see the inlet compressor wheel with a torch. If it looks at all damaged, bent vanes, shiny marks, anything at all then that is probably your noise. Could be the other end (exhaust side) which you can`t see without removing the exhaust header pipe. Takes about an hour to remove the turbo, yours should come off easy if the head has just been off. Studs holding it to the manifold can be a pig.

Budget between £300 and £400 for a rebuilt unit, or if you want to try it you can buy new ones from Germany for similar money. Just had mine rebuilt, whole new internals etc, £380. Mine suddenly got noisy, it had ingested a broken-off part of the inlet hose that had gone hard and brittle and wrecked the impellor. New hose is £35.00

Post by **camper** » 21 Oct 2006, 20:36

Checked the cooling system back flushed what appears to be a recent replacement rad.Replaced the thermostat. Heater gets hot and hoses are hot .The inlet pipe to the rad does get warm/hot the return pipe works okay if the thermostat is removed.Bleed the rad doing the approved method.And having owned and maintained a past t25 1.6n for 11 years have done this on a few occasions .Gut feeling tells me cylinder head problem a leak down test may show it.But the turbo noise makes me think look out for another engine.Thinking of 1.9n or AAZ .

Post by **Westy.Club.Joker** » 21 Oct 2006, 21:00

Just been there M8, decided to get the turbo done in the end. Problem I can see with getting a 1.9 AAZ is the age of them, you can be buying back into the whole cycle of a 10 year old (at least) diesel engine with at least 100,000 miles on it usualy a lot more (people bought diesel cars in those days for economy and doing large mileages) so cracked heads and sh***ed turbos are still a problem. I know a guy who makes a good living from doing diesel heads and there are always plenty of VW 1.9 heads on his shelf, as well as the usual Peugeot/Citroen alloy heads, and Fords.

Would be nice if someone posted a definitive "how to fit the newer TDI engine" along with the correct wiring mods etc in one easy stage,so it can be done easily without a lot of guesswork and minor bodging to get it to work. 110 BHP would be nice

Post by **camper** » 22 Oct 2006, 08:14

Well said regarding an AAZ. If i can obtain a low milage 1.9N it might be the best option as these are more available.

Post by **HarryMann** » 22 Oct 2006, 09:32

Studs holding it to the manifold can be a pig.

These are usually high tensile flange bolts of the very expensive VW kind (£13/ea), 2 long, 2 short or 3 on the triangular ported manifolds.

They can shear on old installationswhen removing, need a very good bi-hex 12mm socket and powerbar (13mm?). Normally torqued up to 45 lb ft I think.

Its not easy on a 50 degree installation getting that cranked inlet hose off, but when it is try rocking the impeller shaft sideways as Westy says, with two fingers. It will normally be the inlet end journals that have the most play, 20-40 thou Ok, 50 or more not rally, but the oil will conceal any play until you really squidge it from side to side. If that nosie is def from turbo then does sound knackered.

Thermostat housing and thermostats themselves always suspect, partic any plastic housings weeping coolant.

AAZs are much stronger generally, provided turbo is a good one.

Post by **camper** » 22 Oct 2006, 13:10

Thanks for your input HarryMann .The turbo metalic noise has gone prehaps the noise was due to high oil flow temp into the turbo when the engine overheated.I will replace the expansion tank cap as i am using the black VW cap that has a slight leakage problem but its okay provided i dont push the engine.As i said the G.S.F expansion cap which was recently purchased was faulty i discovered this after the last time it overheated.I am hoping this may be the only cause .The bolts you mention i was able to undo when i did the head gasket they where 12mm hex.If i replace the engine with a AAZ i would like to keep it with the JX 1.6TD turbo and exhust .But if the turbo is on its way out this means a replacement or couple up the AAZ turbo as discribed how to in the threads.

Post by **HarryMann** » 22 Oct 2006, 15:38

If i replace the engine with a AAZ i would like to keep it with the JX 1.6TD turbo and exhaust. But if the turbo is on its way out this means a replacement or couple up the AAZ turbo as described how to in the threads.

Or you could try to find a decent 2nd hand turbo, though I have to admit, they are as rare as a rare thing. If the engine is cheap and a good one, might be worth spending the money on a refurbed turbo (£350~400). Could look for a good T2 turbo on eBay, but then that is a risk as well, might be NaS, Not as Described

Post by **Westy.Club.Joker** » 03 Nov 2006, 17:05

Alternative for the hyper-expensive VW caphead turbo bolts - get 4 high-tensile 10mm bolts from your local fastener place (cost me £1), with enough thread for the purpose, cut the heads off `em so you have 4 high tensile studs, use these with nuts (17mm socket size) and washers when refitting the turbo. Works for me, the torque setting for these bolts isn`t excessively high anyway, not sure why they use such expensive original bolts. With the 17mm socket you can get a good swing on the nuts anyway, and there is plenty of access and clearance. I would nip the nuts again when it`s hot as well, just to make sure.

As an aside, VW don`t show a gasket for the turbo to exhaust manifold joint, but mine had a thin metal shim type crush gasket, which is readily available from the German specialists, but not over here? My `van is a recent German import, and the turbo had definitely been off before, so this may be where it came from. I re-used the gasket with a smear of sealing compound and tightened it down quickly.

Post by **HarryMann** » 03 Nov 2006, 17:21

Good stuff, and when using exh gasket pastem, dows need to be nipped up quick as you say, I managed without a gasket and seemed to seal well, but flatted off both surfaces to a high degree first

not sure why they use such expensive original bolts

Holding tensile loads at high temps I expect.