V6 Engine Problem

[jackherer 543]

I've got a Xantia with a 3.0 V6 engine that I thought had snapped its timing belt a while ago. I started the engine from cold one morning, it turned once, coughed but didn't fire so I turned the key again and heard the engine spinning pretty fast like it had zero compression. My immediate thought was that it had snapped the timing belt so I roughly marked the alternator belt and the timing belt then turned it over again. The alternator belt appeared to move but the timing belt didn't appear to move. I say 'appeared' because I must have been wrong..... However at this stage I was convinced the bottom end was turning over and the cams weren't. How I could have been mistaken about something like that I can't explain, it seemed pretty clear cut at the time.

 

When I got the engine out I took the remaining cambelt covers off and turned it over with a ratchet on the crank, much to my surprise the entire belt and all four cams turned, so I lined up the timing holes and they are all spot on as is the tension (I've compared it to my new engine). However when I was turning it over by hand it was obvious it had no compression at all, it just span freely whereas the new engine has six distinct compression events as I turn it over. At this point I remembered I had taken out the front three spark plugs (but not the rear three as that requires removal of the inlet manifold ) so I refitted them and tried turning it over again and now it had three compression events where the new engine has six.... So it seems like it has suddenly lost all compression but only on the rear bank, its nothing to do with the timing belt and it happened suddenly from cold, could a cam have snapped maybe? head or block cracked?

 

I'm sure I'll find out whats wrong when I strip it down but thats not going to be for a while yet because for now I'm just going to fit the new engine as its lower mileage anyway, but if it turns out to be something fixable then I will have a spare V6 engine which would have to find a new home somewhere.......

[Miles 331 1 Cars]

Be intresting to see what it was or is,

I;ve got a few V6 engine's now, One as new thank's to ebay and £200.00 so if you get stuck drop me a PM

[jacobs53 0]

yeah sounds like the camshaft has snapped or the cylinder head has cracked. Nothing else I can think of.

 

lee

[Martin@PRD 0]

Each cam shaft has its on verner though im sure from memory they only have a small couner woodruff key to locate into cam shaft. If the spocket is able to turn with out the cam shaft then all compression maybe leaking into exhaust ports

 

Personaly I would revmove inlet manifold and cheak whether it has got spark plugs fiited correctly in the rear first.

Edited December 11, 2006 by Martin@PRD

[Malachy 0]

Each cam shaft has its on verner though im sure from memory they only have a small couner woodruff key to locate into cam shaft. If the spocket is able to turn with out the cam shaft then all compression maybe leaking into exhaust ports

 

Personaly I would revmove inlet manifold and cheak whether it has got spark plugs fiited correctly in the rear first.

 

yeah but the drive is not from the woodruff its just location, its a common misconception that woodruffs transmit drive. Th friction from the bolt>pulley transmit the drive.

 

ps sorry for poor typing my laptop keyboard is fubard

[Martin@PRD 0]

yeah but the drive is not from the woodruff its just location, its a common misconception that woodruffs transmit drive. Th friction from the bolt>pulley transmit the drive.

 

ps sorry for poor typing my laptop keyboard is fubard

 

Thats right, though if the bolt was incorrectly torqued this is would course a problem, At some stage they changed to cam shaft bolt to left handed thread as both of my v6's has each type and the later one has more webing on the exhaurst side of the clylinder head