[Hairy]

Gday,
Ive noticed a rattle coming from my engine which has got fractionally worse the last time my son drove it down the beach.
I think its valve/ rocker arm clearances,n so plan on taking the rocker cover off and checking the gaps.
I noticed it only happens under load.......in soft sand as you loose revs because of too low a gear and holding the accelerator flat????
Does that sound like a fair diagnosis, or is their something else I should check first?
Its a 1997 SJ80 with a G13BA engine.......
Does anyone know what the valve clearance's should be?
And its been a long time since Ive done valve clearances too.........I think I used to take the spark plugs out, wind the motor over by hand with a screw driver in say pot 1 until the piston is at the top of the stroke and check the valve clearences at that pot????? With engine warmed up first........Does that sound about right?

Cheers

[Bruce]

I would check the timing first. I would guess that it's too far advanced.

[Blkfxx]

Hairy wrote:

Gday,
in soft sand as you loose revs because of too low a gear and holding the accelerator flat????

Sounds like pre-ignition/detonation/pinging

search.php?st=0&sk=t&sd=d&sr=posts&keywords=pinging

[Hairy]

Bruce wrote:

I would check the timing first. I would guess that it's too far advanced.

Ahhh....yes.
Its been a long time since Ive played around with petrol engines.....and I think you've hit the nail on the head!
I bet I cant even find my old timing light though.....

Cheers

[Hairy]

Blkfxx wrote:

Hairy wrote:

Gday,
in soft sand as you loose revs because of too low a gear and holding the accelerator flat????

Sounds like pre-ignition/detonation/pinging

http://auszookers.com/forum/search.php? ... ds=pinging

That would probably have something to do with the high idle too , wouldn't it?

[Hairy]

Bugger........I reckon I gave away my timing light and vacuum gauge before I moved.......might have to buy a new one.....Cheers

[Blkfxx]

Yeah it most likely has something to do with your high idle.

[just_cruizin]

Just to throw a grenade through the door. The late G13's had a nasty habit of breaking piston skirts which first shows as a rattle under load. Check your timing first as an easy check if it's all good this is another cause

[Gwagensteve]

^ This would be my guess too.

If it's an irregular "tink" kind of rattle that's very sensitive to throttle position (i.e vacuum advance) it's pinging or "pinking" which is related to fuel quality and/or excessive timing advance.

If it's a constant coarse gravelly rattle at all times the engine is under load I'd call piston skirts. They're notorious for dropping them.

If the timing checks out OK (10˚) and it has good fuel I'd be temped to pull the sump and go looking for chunks of piston.

[Xr6_matt]

I have this problem in mine, Suzi mechanic diagnosed it as timing problem, it only happens under load with the foot to the floor, back it off a little and it goes away. I'll get around to getting it fixed one day..

[Gwagensteve]

I'd get it fixed sooner rather than later. Pinging is hard on valves. Takes 30 seconds to do the base timing.

[Hairy]

Thanks for all the replies.......
By the sounds of all that Im fairly confident its just timing so have just bought myself a new timing light.
Ill reply later to let you know the results.
I watched a video on you tube and apparently there is a timing mark on the side of the block too????
Does this https://www.youtube.com/watch?v=17sfS1Cz3gQ sound like the correct procedure for me?

Cheers

[Hairy]

Ok....I checked the timing and it wasn't too bad.....took it for a drive yesterday, and I reckon the rattling was worse.
Where I noticed it worse was going along the bitumen, up an incline, with the foot flat to the floor in top gear, loosing revs.
Im starting to think piston skirts for some reason, except that it doesn't seem to do it while the revs are up, flogging around the sand hills???
I would have thought bits of piston in your sump would have been worse at high revs....not as your loosing revs????
I suppose the next easiest thing is a quick look at valve clearance's then off with the sump!
If it is the piston skirts.....is it alright to drop the oil....discard any pieces of piston and keep it running for a few weeks? Or do they just get worse until something really bead happens????
I really planned on doing a lot of fishing in it over the next couple of weeks...not working on it!!!!

Any ideas would be greatly appreciated.......

Cheers

[atari4x4]

bung in some 98ron & see if that settles the pinging down.

[Hairy]

atari4x4 wrote:

bung in some 98ron & see if that settles the pinging down.

Ok Ill give it a shot

[Gwagensteve]

If the timing is right and it gets no better on 98....

[Hairy]

Yafuckinghoooo!!!!!!!


I retarded the timing and hey presto............No more rattle.
Im not sure on exactly how many degrees it is as it depends where you hold your head to what reading I get but I reckon its about 8 degrees or maybe a fraction lower.
Ill try the 98 octane fuel during the week and see if I can further advance the timing I guess.

Thanks for all of your help!

Cheers

[atari4x4]

Gwagensteve wrote:

If the timing is right and it gets no better on 98....

it's summer, we go look for skirt?