Outer Limits 4x4 Board

My pajero race car NJ 3.5L DOHC V6, had it running in the shed last week. Went to start it this week and take it for a run. Just wound over, like no compression. I thought timing belt (has only done 1500km or so of race kms). Pulled covers off, not broken. Found a frog had been in the timing belt cover and been fed through the belt. Didn't look like cam teeth had skipped, but there was frog everywhere.

Pulled belt and crank angle sensor (it looked a little stuffed from frog going through it) off an cleaned it all up, hydraulic tensioner looked fine. Refitted timing belt looked fine. Still seems like no compression.

Does a crook crank angle sensor make it seem like no compression (I'm thinking not)? Usually it is quite slow to wind and hard to turn crank with a socket bar. But it just free winds at the moment, and turns easy by hand. I pulled a plug out and was pretty wet with fuel, seemed like plenty of spark. Cranked it over, didn't seem to have intake suction.

Might have trouble trying to compression test it as the plugs are nearly 100mm down in the heads. To me it might have skipped crank teeth and put the timing out maybe worst case scenario bending valves? It didn't seem to make any horrible noises when trying to start it (only wound it over for 30 seconds or so all up), it just wound freely. I am kicking myself I didn't get the hose and clean it properly and look before dropping the timing belt.

Have anyone struck this before? Do i need to pull the heads off or is it something simple that i have missed. I replaced the timing belt when i got it and has ran fine ever since, so as far as I can see I have refitted it right. I wll pull the heads off if I have to but don't want to obviously if it could be something else.

Any ideas would be a big help!

Cheers.

Crank angle sensor (and cam angle sensor) has nothing to do with compression. All they do is determine that the crank is at the position ready for the spark plug to fire, and the cam angle sensor confirms that the camshaft is still turning (you haven't broken a timing belt). You may have stuffed the crank angle sensor (I doubt it) by yucking it up with frog guts. If that is the case, you are likely to either get no spark, or get it in funny places ie not when you need it for the specific cylinder at the specific time.

Were the timing marks on the camshaft pulleys still lining up at TDC? If they were, you were unlikely to have bent any valves. If you have bent valves, that could account for the lack of compression. I am glas it is you, noy me - best of luck with it.

Pulled car apart futher tappett covers off, roller rockers on inlet side wanted to fall out with no cam pressure. All inlet valves are bent, who would have thought that winding it over for 30 seconds or so would have bent valves. All I could put it down to is that frog was a big frog) went through timing belt and spun crank timing gear upon start up, therefore carnage in valve train.

Dissapointing as it ran fine last week and went to start it saturday and it looks like thats when the damage happened. Anyone with a entire DOHC motor or motor with bottom end damage laying around?

Not wishing to bring bad news, but I would expect that the pistons may be stuffed as well as the valves. Nasty job. You only need one revolution to do that sort of damage, not 30 sec worth. Even so, the frog must have been solid to cause the belt to jump. Whatever, my condolkences to you over this issue. Hope you can sort it out soon and cheaply.

Since it is your race machine I feel this is a silver lining situation..... Almost like an excuse to the boss that the engine needs work and a supercharger...

I have a couple of 24V heads that would be useable .. I replaced my last engine whole as a 60,000 K old 24V SOHC magna motor was only $800 ... why bother with pulling stuff part when a motor is so cheap..

the heads are in Wangaratta, North east vic if you want em .. I can pull em off and get them freighted of your keen ( You pay freight of course)

Cheers
Guy

NJV6 wrote:Since it is your race machine I feel this is a silver lining situation..... Almost like an excuse to the boss that the engine needs work and a supercharger...

I have thought about that, would be twin turbo or V8 not supercharged. But then have to run class 8 offroad (extreme 4wd) which basically just needs to look like a production 4wd with any engine or suspension mods. So would need to spend big $$$$ to be competitive.

love_mud wrote:I have a couple of 24V heads that would be useable .. I replaced my last engine whole as a 60,000 K old 24V SOHC magna motor was only $800 ... why bother with pulling stuff part when a motor is so cheap..

the heads are in Wangaratta, North east vic if you want em .. I can pull em off and get them freighted of your keen ( You pay freight of course)

Cheers
Guy

I would be straight onto the magna engine swap if my engine was a SOHC 3.5, but mine is the DOHC (quad cam) V6, which is less common in pajeros and not used in magnas. Thanks heaps for the offer but your heads wouldn't be any good for my engine.

From what I have read the sohc and dohc cam heads are interchangeable .. unless they had the variable valve timing etc ...

Could be wrong though ... has happeded quite a few times before ... just ask my wife

The SOHC heads would have only one set of pedestals for the camshaft. The DOHC heads will have two, therefore they must be different. ALmost certainly, you will be able to bolt a SOHC headonto a DOHC block, but oyu are going to have fun trying to get the timing belt to work properly.