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GBMUD
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My cam belt broke at the weekend

So, I fitted a new cam belt, tensioner and push rods to the Tdi. No problem. :) I made sure that all the marks lined up and that the tensioner was set with the correct torque. No problem there, done it before. I put the front cover back on and the water pump and then set about setting the tappets. Using the rule of 9, 1 and 3 were rocking so I adjusted 8 and 6. Then I turned the engine to see which rockers rocked next but there was a gentle clunk and I felt resistance. Ah, I thought, I must have set the timing wrong but thinking about it, I was (and still am) sure it is OK. I then concluded that the tappets were so tight that they were holding the valves open and interfering with the pistons. I loosened all the tappets to be sure that all the valves were closed and was able to continue as normal with the engine rotating freely, which was a relief. :)

Once the tappets were set I thought I should have a quick try of the engine to see that all was OK before completing reassembly of the cooling system and all the pipes and hoses. The engine cranked but did not fire. Now my heart really sank but as it became clear that the battery was flat I rallied my spirits. I put the battery on charge and completed the job before trying the engine again. It burst into life and ran fine for a few seconds before I turned it off. Then I had to go pick wife up from the station, a job for the car.

When I got back I started the Landrover again and all was still well. I backed out of the drive for a quick run around the block before checking the coolant level again. About 300 meters up the road, what felt like a misfire became apparent and I turned around and headed home. By the time I got home the misfire was quite pronounced and there was a knocking sound from the engine as well as a peculiar induction sound. :( Now I am wondering if there is something badly wrong, if I have caused it by poor fitting or if it is some damage that happened as a result of the belt breaking. Did some foreign body get into the inlet manifold and then get blown into the system by the turbo winding up?

While I was making tea, a thought occurred to me. The mis-fire seemed to come on gradually rather than suddenly, not like something breaking. Perhaps it could be a tappet having come loose thereby preventing one valve from opening properly and making the odd noise in the inlet? One of the ones I had adjusted already and failed to tighten properly? Do you think that 2 minutes running could cause a tappet to unscrew completely enough to prevent that cylinder firing? Please say you think so. My money would be on an exhaust valve, perhaps number 4 exhaust, just based on the order I set them in...

Please excuse any apparent lack of coherence, I have been drowning my sorrows. :D

Chris

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My cam belt broke at the weekend

Do you think that 2 minutes running could cause a tappet to unscrew completely enough to prevent that cylinder firing? Please say you think so. My money would be on an exhaust valve, perhaps number 4 exhaust, just based on the order I set them in...

Chris

First thing I thought of... 2 minutes = (maybe) 3000 smacks, enough to loosen anything I'd say...

I'll keep my fingers crossed for you

Rog

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Please say you think so

i think so.

look on the bright side at least you didnt hit the wall when reversing out of the driveway!

Sorry to hear its not well, you can borrow mine for the pyrennes if you like

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could be a loose valve adjuster or 1 has lost is ball end that sits in the pushrod cup or maybe a pushrod wasn't fully engaged & has jumped out & 1 valve can't open, whip the rocker cover off again & check all the pushrods are fully seated with the rocker adjuster screw ball ends. as it's run doubt it's anything deadly serious, :unsure:

best wishes for a speedy fix :i-m_so_happy:

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i dont know if your engine had them, but if you had the valvestem caps that some Tdis had make sure you still have all 8. if the tappet was loose you can loose a stem cap dead easy giving a massive loss of valve movement.

of course the other option is the stem cap could have been cracked when the belt went & fell apart when put back into service.

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You possibly have broken a rocker Chris. They don't always break immediately. The sort of noise a diesel makes when it's running on 3 is a metallic clattering noise as the compression trapped in the cylinder tries to go out the wrong way.

A broken valve cap could be the culprit as well. One breaking would suddenly give you a tappet gap that's increased by 1mm or so, but I think the valve would still open, so just a noisy tappet, rather than what you describe.

Les :)

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Thanks guys. :)

No James, I was tucked up in bed (just) at 0657; but as soon as I get back from the school run I will be on it. It is windy and wet here this morning. :(

I do not think it is a missing cap, I was very careful not to loose any and to be sure that they were in place when I set the tappets. Time will tell if one has disintegrated... it may have done.

Thinking about it in the night, when I first noticed that there was a problem it was under power and when I let it back to tickover it ran smoothly and quietly again. A few seconds later it was present all the time. Perhaps I am clutching at straws but that re-enforces my supposition about the tappets.

Chris

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Sometimes it is possible to accidently set the tappets with the bottom of a push rod sat on the lip of the tappet in the block rather than in the socket. Once the engine has run the push rod can jump down into the socket, resulting in a massive gap at the rocker. Perhaps this has happened?

Hope it is something simple,

Regards,

Diff

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Sometimes it is possible to accidently set the tappets with the bottom of a push rod sat on the lip of the tappet in the block rather than in the socket. Once the engine has run the push rod can jump down into the socket, resulting in a massive gap at the rocker. Perhaps this has happened?

Hope it is something simple,

I love you guys. :) Diff, as far as I can now tell, you were spot on. Have a gold star. :D

I took the rocker cover off and both tappets for number 1 had gaps you could have driven a bus Petal through. The valve caps for both were missing, I discovered them cowering together under the rocker shaft. I reset all the tappets and gave the engine a quick run to make sure the bad noise had gone away. This is when I learned a big lesson.

I had used a ratchet and socket to turn the engine over by the front pulley while setting the tappets and I had forgotten to remove them before starting the engine. Needless to say, there was a big bang and I now have a big hole in the fan cowl and need a new fan. :( The big crank damper bolt came undone despite having had a good tightening with a breaker bar and some tube. What will a take from this? Always DOUBLE check BEFORE starting the engine!

I have made a short test run around the block and all seems to be in order. The engine seems to be running quieter and smoother than it has for a long time. I am not sure if the old cam belt idler was making a row, the fan was noisy or the old waterpump was making some noise - I suspect a combination of all three. I have to go for a longer run (into Bath) later so time will tell - I just hope I do not get cought in traffic since I am now fanless...

Thanks again all. :)

Chris

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I love you guys. :) Diff, as far as I can now tell, you were spot on. Have a gold star. :D

I took the rocker cover off and both tappets for number 1 had gaps you could have driven a bus Petal through. The valve caps for both were missing, I discovered them cowering together under the rocker shaft. I reset all the tappets and gave the engine a quick run to make sure the bad noise had gone away. This is when I learned a big lesson.

I had used a ratchet and socket to turn the engine over by the front pulley while setting the tappets and I had forgotten to remove them before starting the engine. Needless to say, there was a big bang and I now have a big hole in the fan cowl and need a new fan. :( The big crank damper bolt came undone despite having had a good tightening with a breaker bar and some tube. What will a take from this? Always DOUBLE check BEFORE starting the engine!

I have made a short test run around the block and all seems to be in order. The engine seems to be running quieter and smoother than it has for a long time. I am not sure if the old cam belt idler was making a row, the fan was noisy or the old waterpump was making some noise - I suspect a combination of all three. I have to go for a longer run (into Bath) later so time will tell - I just hope I do not get cought in traffic since I am now fanless...

Thanks again all. :)

Chris

Chris -

If your viscious coupling isn't damaged, I have a spare Tdi fan buried somewhere in the workshop which you are welcome to have.

Matt

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A twin viscous fan setup, mmmm, interesting. :) Thanks guys, whoever I see first, please bring it along... :)

You speak too soon Mr Warne.

Further upset this morning on my way to Bath, there seems to be some lack of power - would only just struggle to 40. I investigated when I got there, making sure that the pipes to the fuel diaphram were OK and discovered what looked like the Exxon Valdez disaster. In my excitment at not having a ruined engine, I had not tightened down the rocker cover. That done, there was nothing much else to see so I checked the performance of the fuel lift pump - it seems a little lack luster so that is my next job. As a back-up to this theory, one would reasonably expect some smoke from the exhaust while climbing steep hills under load; I had none suggesting that there was not a whole load of fuel there. I have a lift pump here somewhere...

Fingers crossed for me?

Chris

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Well, the lift pump seems OK. I disconnected the feed into the fuel filter and ran the engine and the fuel pump produced about a pint of fuel in about 30 seconds running. I bled the filter - where there was some air - and put it all back together. It all seems OK now although I have yet to try a high speed run. Just in case, I have treated it to a new fuel filter. Why it was running out of power is a bit of a mystery though.

Chris

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Well, the lift pump seems OK. I disconnected the feed into the fuel filter and ran the engine and the fuel pump produced about a pint of fuel in about 30 seconds running. I bled the filter - where there was some air - and put it all back together. It all seems OK now although I have yet to try a high speed run. Just in case, I have treated it to a new fuel filter. Why it was running out of power is a bit of a mystery though.

Chris

Probably an air lock in the feed pipe ;) …….. so you may have sorted it.

I know you don’t want to hear this :ph34r: , but the engine pump timing being retarded by a couple of teeth also gives the same symptoms……….

Ian

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