P38, 4.0 petrol, 2002, Bosch - no start

brianp38dse · Jun 18, 2020

I think you found your problem

that is a very clean break, wonder what caused it to go, does not look like cam bearing bearing failure.
hopefully no more damage elsewhere.

Shippers · Jun 18, 2020

Jock85 said:
They all appeared level and from what I could see there were no impact marks on the pistons so I'm of the same mind to give it bash.

Heads still on?...camera down plug hole?...i'd go for new cam and turn over by hand and watch and feel for drag...I had a snapped sparkplug in my 101 V8 po fitted long reach and it had locked down had to remove head took it to a local guy as I couldnt get it out he only does head refurb..told by others it need skimmed and do both etc...he said no as the problem was not with gasket failing but plug...looking round his shop and seeing his equipment and performance heads ready for collection was an eye opener all in the basement under his house...plug out collect next day 20€...

Grrrrrr · Jun 19, 2020

Jock85 said:
They all appeared level and from what I could see there were no impact marks on the pistons so I'm of the same mind to give it bash.

On the list. Along with about 20 other things. Seized oil cooler pipes had me raging...

Those oil cooler pipes always oxidise and seize. Often easiest to just ditch the bloody lot and replace. Exhaust manifold heat shield bolts are usually f@ckers too.

Datatek · Jun 19, 2020

Never seen a camshaft snap

Must be Land Rover quality

Gord Wedman · Jun 20, 2020

That is pretty unusual. I had a Jeep with a V8 engine once suddenly produce only 10 psi of oil pressure instead of the usual 50. After removing the oil pan, and also checking the pump which was part of the front cover, I finally took off the valve covers and discovered a broken rocker arm had let a lifter almost pop out of its bore. All done outside during a winter in Ontario.

Grrrrrr · Jun 20, 2020

Datatek said:
Never seen a camshaft snap Must be Land Rover quality

Nor I. Another thing to worry about on the v8!

Jock85 · Jun 22, 2020

Just waiting for the delivery of replacement parts to arrive so I'll let everyone know if it's a success.

I also did a leak down test on Saturday. About 10% loss across all 8 cylinders so on the plus side it seems the snapped cam didnt cause any crushed valves. Amazing really

Datatek · Jun 22, 2020

Jock85 said:
Just waiting for the delivery of replacement parts to arrive so I'll let everyone know if it's a success.

I also did a leak down test on Saturday. About 10% loss across all 8 cylinders so on the plus side it seems the snapped cam didnt cause any crushed valves. Amazing really

To check for damaged valves, you need to do a compression test

Jock85 · Jun 22, 2020

Datatek said:
To check for damaged valves, you need to do a compression test

Hmm, im not able to do a compression test until its reassembled but would a bent valve not result in a higher leak?

Datatek · Jun 22, 2020

Jock85 said:
Hmm, im not able to do a compression test until its reassembled but would a bent valve not result in a higher leak?

If by a leak off test you are referring to an injector leak off test, there is no connection that I am aware of between that and a loss of compression due to a bent valve.

Mark Piercy · Jun 22, 2020

Jock85 said:
Hmm, im not able to do a compression test until its reassembled but would a bent valve not result in a higher leak?

You can do a compression test with camshaft out of the engine. It may not be an exact figure but it'll tell you if you have a damaged valve or 16!!
Just make sure you have no rods on the engine... Can't remember their names??? For the rockers...

Jock85 · Jun 22, 2020

Datatek said:
If by a leak off test you are referring to an injector leak off test, there is no connection that I am aware of between that and a loss of compression due to a bent valve.

I think we're talking about different tests. My test was pressurising the cylinder via the spark plug hole and determining the amount of air leak passing the rings, valves, head gasket etc.

Mark Piercy · Jun 22, 2020

Jock85 said:
I think we're talking about different tests. My test was pressurising the cylinder via the spark plug hole and determining the amount of air leak passing the rings, valves, head gasket etc.

Cylinder leak off test, yes you can still do that with no camshaft.

Don't forget all your valves will be shut

Grrrrrr · Jun 22, 2020

Mark Piercy said:
Cylinder leak off test, yes you can still do that with no camshaft.
Don't forget all your valves will be shut

Yes, so no air should be escaping other than past the rings.

Jock85 · Jun 27, 2020

Right, so I went to start fitting the new camshaft today and i believe I've discovered why it snapped. The cam journal bearing between the second and third bank seems to have slipped round to 12o'clock (the others are all at 8o'clock) , blocking the oil passage and causing the cam to bind. I'm not really sure what to do next. I suppose if anyone knows if the bearings can be replaced with the engine in place would let me know if it's worth while pursuing? I think if the engine has to come out I probably won't take it any further.

oakey · Jun 27, 2020

Well done for finding it.
Nice to know the cause.
Sorry no idea about your question but seems a shame to scrap her

Shippers · Jun 27, 2020

Cant help on that one...but are you sure the bearing didn't move when cam snapped?...

Jock85 · Jun 27, 2020

Shippers said:
Cant help on that one...but are you sure the bearing didn't move when cam snapped?...

I dont really have any reason to think so. Whatever happened the binding must've increased the twisting stresses from the dry running causing it to give way I reckon. At least that's the best I can make of it.

Marshall8hp · Jun 27, 2020

The bearings are replaceable but I think need to be line bored. Give Chris at RPI Engineering a call and have a chat, they are good guys and should be able to shed some light for you and give you some options.

Grrrrrr · Jun 28, 2020

Jock85 said:
Right, so I went to start fitting the new camshaft today and i believe I've discovered why it snapped. The cam journal bearing between the second and third bank seems to have slipped round to 12o'clock (the others are all at 8o'clock) , blocking the oil passage and causing the cam to bind. I'm not really sure what to do next. I suppose if anyone knows if the bearings can be replaced with the engine in place would let me know if it's worth while pursuing? I think if the engine has to come out I probably won't take it any further.

Any pictures?!

P38, 4.0 petrol, 2002, Bosch - no start

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