95 3.0l lx timing problem after hitting rock

[95caravelle95]

last weekend we hit some rock in my 95 caravelle with a 3.0l lx motor. the prop was pretty messed up but the boat never stalled. about 5 minutes later, the boat was turned off, and it would not start after that. i had it towed to the dock and took it home. i checked the timing with the timing light and the timing had advanced to about 10-12 degrees ATDC. is this a normal occurance when you hit something? Is it "normal for the timing to be messed up in the impact?

also, what should i be looking at or worried about internally in the engine? is it a timing chain or belt also, thanks in advance.

any help for this newbie would be great!!

 

[thrasher]

Re: 95 3.0l lx timing problem after hitting rock

I cannot see how hitting a rock can change the ignition timing.. If the cam timing chain did jump a tooth, then the chain needs replacing! There should never be enough slack in the chain to be able to jump a tooth, however that sounds really unlikely (I have never heard of it happening on a car engine! Not that many car engines hit rocks).

If I understand correctly, the normal timing is around 8 degrees and you say it advanced to 10 or 12 degrees so we are looking at a 4 degree change.
If we are looking for a one tooth slip to advance 4 degrees, then the timing gear would need to have at least 90 teeth (360 degrees / 4 degree = 90) to allow a 4 degree slip. Last time I looked, the timing gear (assuming this engine has a timing chain and not a toothed belt) has a lot less than 90 teeth, so again I doubt its a slipped timing chain.

I don't know what the Volvo 3.0L engine looks like, so I am having a hard time guessing what could cause the timing to advance 3 or 4 degrees.
Are you certain the timing was correct before you went out on the boat?

Gary

 

[Don S]

Re: 95 3.0l lx timing problem after hitting rock

Assuming you have the Delco EST distributor in that engine, did you put it in base timing mode before checking the timing? If not, then you don't know if it's right or wrong at this point.
Put it in base timing mode and recheck and make sure it's right on the money.
Here is the OEM service manual for your engine.
http://www.boatfix.com/merc/Servmanl/13/13covr2.pdf go to section 4B page 21 for the EST distributor

 

[Wotam]

Re: 95 3.0l lx timing problem after hitting rock

>"I cannot see how hitting a rock can change the ignition timing"

I've heard stories of GM engines twisting a distributor shaft due to a backfire... but getting that sort of impulse back to the engine from hitting a rock would have to be pretty darn catastrophic.

 

[95caravelle95]

Re: 95 3.0l lx timing problem after hitting rock

I am not POSITIVE the timing was correct before going out, but ive put 25 hours on the boat in the past month without any problem at all. after the rock was hit, the boat kept running. it even idled fine. i turned it off, and a few minutes later, it would not start. how do you tell on that little metal tab with the "teeth" on it where 0tdc is? mine is rusted and i cannot read it, i assumed tdc was in the very middle.

i did put it into base timing mode and set the timing. I had to turn the distributor to get it into time but now it starts right up and runs great.

someone told me I could have messed up the gear on the end of the distributor.

also, is the Merc 3.0l lx a interference engine? do i need to worry about bent valves?

thanks

 

[bruceb58]

Re: 95 3.0l lx timing problem after hitting rock

Your first post said 10-12 degrees ATDC and you should be 8 degrees BTDC. The timing would actually be more retarded! That is a huge difference! I would be surprised if that was actually the case.