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TDI has just gone bang - advice needed


RXStdi
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After 125k our Lupo TDI has just gone bang and am not sure whether it is worth fixing so thought I would ask for advice.    It is one of the early cars (2001) and was in reasonable condition except for rust starting on wheel arches but diesels seem to be out of favour now and I am finding it difficult to get an idea what it would be worth if I fixed it?

The cambelt was changed approx 40k ago (by a garage) and the cambelt still looks fine but the stud holding the cambelt tensioner had sheared off totally allowing the belt to jump.   I have just got around to pulling it apart and it has bent almost all the valves but the tops of the pistons look OK and the engine turns over fine now I have the head off.

I reckon I could pick up a secondhand head OK but with the cost of cambelt kit, head gasket and head bolts it looks like being a costly repair so not sure if it is worth it.  Did think about a secondhand engine but if I got one I would need to do the cambelt anyway for peace of mind.

 

Any words of wisdom?

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are diesels really out of favour generally. I know they have had some negative press but it would not stop me buying one, I feel a lot of people out there would still buy one for the better fuel economy and superior torque, particularly if they have had a diesel before. when it comes to money there are plenty of us out there who put our own pocket first and not whether we will pollute the planet.  If it was mine I would probably have a go at fixing it unless I knew the car had a lot of other issues that would need money in the short term and make the whole lot uneconomically worthwhile.

A friend of mine had a rover diesel which ended up with a load of bent valves, he put the valves in  a vice and hammered them straight. Amazingly it all seemed fine after reassembly. I think the only two things he bought were a new timing belt and a new head gasket.

Another friend had a Mk3 Escort (CVH engine). a load of bent valves which he hammered straight and a load of bent rocker arms (these are thick pressed steel). he hammered the rocker arms straight. some of them had split where bent, so he welded the splits. all worked when back together but after a while there were problems caused by valves not opening fully. this was because his welding on the split rocker arms was insufficient (a poor migweld without enough penetrartion), so he bought some secondhand rockers and fitted them and all was fine. I used the car myself for about 2 years after this.

If you have gone this far with dismantling you may as well go for it (mind you I have no idea what a head and gaskets will cost you). but why did the tensioner stud shear? and can you you sort that out easily (I don't know how accessible)

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4 hours ago, RXStdi said:

After 125k our Lupo TDI has just gone bang and am not sure whether it is worth fixing so thought I would ask for advice.    It is one of the early cars (2001) and was in reasonable condition except for rust starting on wheel arches but diesels seem to be out of favour now and I am finding it difficult to get an idea what it would be worth if I fixed it?

The cambelt was changed approx 40k ago (by a garage) and the cambelt still looks fine but the stud holding the cambelt tensioner had sheared off totally allowing the belt to jump.   I have just got around to pulling it apart and it has bent almost all the valves but the tops of the pistons look OK and the engine turns over fine now I have the head off.

I reckon I could pick up a secondhand head OK but with the cost of cambelt kit, head gasket and head bolts it looks like being a costly repair so not sure if it is worth it.  Did think about a secondhand engine but if I got one I would need to do the cambelt anyway for peace of mind.

 

Any words of wisdom?

get an engine off ebay or from someone who's breaking a car. while your's is in bits, you would probably be tempted to redo all the service stuff anyway, so not a big deal which lump you do it all on. if the car's in good nick, it's probably worth about 1k. engines are about £125 delivered. you just need to swap them over now.

i wouldn't risk it. you may have a crack in a bearing shell retainer or even one of the bolts, or a bent con rod....

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Thanks for all the replies.

Not decided what to do but really feel I should fix it as we are attached to the car and have owned it almost from new - as someone has pointed out I have done half the job already.  The broken stud is not really a problem as it is on the head rather than the block but the head bolts are single use so by the time you add in these plus head gasket set and cambelt kit it is well over £200 and also need to buy a decent secondhand head (and there is always something else needed that you forget about)

The failure was unusual and seems to be simply metal fatigue as the cambelt and tensioner were well within service limits and other than the damage caused by the breakage seemed fine.  I usually do my own cambelt changes but the last one was done by a VW dealer as I was laid up with a bad back at the time.  The cambelt kit normally includes the idler roller and retaining bolt but only the nut for the tensioner  - I will always renew the stud as well in future.

 

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Those are good prices - where are they from?

I looked on Eurocarparts and they are quoting £165 for cambelt kit (I need the one with the hydraulic damper), £75 for head gasket set and £31 for the head bolts - I would obviously try to buy when they have one of their discount offers on.

Do not think it would be a problem getting the stud out as it has not snapped off flush with surface and I have a MIG welder but not sure about replacing valves as the bent stems must have caused some damage to the valve guides?

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"ajusa" gaskets are very good. good for motorsport use too. imho better than oem. you can double crush them (tighten/release/tighten) even when running high compression ratios.

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Lots of useful info - thanks.

I had to do the head gasket on my old Golf TDI last year and used an OEM head gasket from TPS for peace of mind as the early cars like mine have a bit of a reputation for HG problems so will probably do the same again.

I managed to take a few photos at the weekend but it is difficult to show the detail.  The first one shows the broken stud for the tensioner and it seems to be simply due to metal fatigue and the tensioner then damaged the damper assembly as well when it dropped.  When I was looking at the cost of parts I noticed that the cambelt kit from INA now includes this stud so maybe failure is more common than I thought.

 

I have not yet stripped the head down but it is obvious that most of the valve heads are no longer central to the seats and I can only rotate the camshaft a small distance.     Think I will probably look for a decent secondhand head rather than repair mine.

Have also taken some photos of the tops of pistons to try to show the slight marking to piston crowns but do not think this is a problem?

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Probably cheapest option would be find another engine for £150 - £250 and get £100 or so for yours or break it and get even more. More work to change the engine but no hidden problems like cracked pistons etc.

I'm after a working bottom end myself.

Edited by Sausage
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and if the valves are bent, your cam may be running eccentric....

so all the following problems may have been banked: (rich hates lists)

damaged valve seats, cracked pistons, bent con rods, cracked or deformed main bearing shells, damaged big end shells, eccentric camshaft, valve train damaged, sleeves damaged... + probably some others i cant think of.

=> engine swap best bet.

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admittedly my belt once sheared and I just opted for a replacement engine.

sounded better, tighter and faster afterwards.

if I was happy with the engine I would do valves and see what happens.

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Think I am inclined to agree with Rich (he gave me advice on fixing an ECU problem around 5 years ago when my wife (KermitGirl) had the car and it was still working fine before this failure).     The bottom end looks to be pretty strong on these engines and think it is worth taking a chance on it being OK - not sure about the top end so will probably opt for a secondhand head if I can find one.   Anyone know whether I could use a head from a later car like a Polo TDI?      Always feel that a secondhand engine is a big gamble anyway unless you can hear it running or buy it from someone you know.

I will probably strip the head down this weekend to find out how bad the damage is.  Thanks for all the input.

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