2TG Camshaft dowels missing????

[rmwood7]

The chain tenshioner on the camshaft just broke off while I was driving.
Stopped immediatly and swore. tow truck more swearing!
So managed to get a new one from Sleeka Spares and replaced it, while turning the motor over by hand I noticed the exhaust cam didn't move, dowel busted I thought, but no, there wasn't one in it.
Its a wonder the motor ran at all, there is no way the dowel could have come out on its own?
The motor was rebuilt by the previous owner.
Any Ideas about
A tenshioner breaking.
B where we get new dowels from.
Cheers Richard

[fixeruperer]

new dowels from toyota, if not, ask a fellow 2tg owner what size the dowel is, it will prolly be the same as another toyo engine, then order one from toyota. or machine one up.

where did the tensioner break ?

[rmwood7]

Picture%20012.jpg
Thanks for the reply,
Sleeka Spares stock them.
Just snapped off, like someone had overtightened it, I am thinking the dowel fell out got entangled in the chain , made it taught and just popped the tenshioner out, so I may be taking the timing over off as well.

[71TA22]

Dowels are 6mm x 15mm.

For the dowel to fall out the dowel lock washer cant have been set up properly.

Beware of bent valves (may only be a very slight bend at the valve head) as a result of this incident. Engine will run at idle but will get progressively worse with revs. Compression test.

[rmwood7]

Thanks Mike
I have ordered new dowels.
Yes the washer properbly was out , good idea ,compression test, I may recondition the motor if they are bent.

[MorGo]

For sure the valves are bent (probably on both sides).I have made mark on the wall when in comes G-head with straight valves.. so far there is 1 "X"..
All the dovels are 6 mm diameter.
Many times when timing the cams the dovel drops:as long as you heard it to enter oilpan no problem;it stays there.Just get new dovel.The trouble starts when you don't hear dovel enter the oilpan;then it is somewhere in the timing chain and WILL destroy more than you want to know if tried to run the engine.So it's dismandling time;you take it apart so long that you find that dowel.

If you are bold enough you don't use dovels! I once opened 2T-G what didn't have dovels;the gear retaining bolt were just tightened so hard that the gear stay put.Were run tens of thousand km's

[jb_22]

I had a tensioner break off too, but further down on the thread where the adjustment nut is. I suspect somebody over-tightened the locknut & tried to use it to remove the tensioner. The hex part on the base on earlier heads can be hard to get to if you're using a big spanner.

If the dowel fell out and locked up the timing, I'd be replacing the timing chains too, they're only $85 delivered for both chains. Then you might find where that dowel went too. When you replace the dowel, use a rag stuffed down the head to save you dropping the dowel into the motor.

[rmwood7]

Thanks for all your good advise.
Removed Timing cover, no dowel, chains look ok, well it all looks ok, so it has dropped into the oilpan or there wasn't one, there is one in the inlet cam.
We don't really know what to do , setup timing with new dowel , turn the motor over by hand, if thats ok then do compression test??
Save up and tow car to engine reconditioner??

[71TA22]

Remove spark plugs and cams. Re-set cam timing with new dowel. Turn over a couple of times by hand then re-check timing. Then compression test.

If it was me I would just take the head off and re-do. Far and away the best insurance for your engines health.

I have had valves which have moved freely in their guides but have been slightly bent at the head by interference contact. Only way to tell is by compression test or head off, remove them and check.

Slight bend reveals itself when you grind the valve head. Grind surface is not concentric. Bent valve head on right in photo's below.

[rmwood7]

Amazing photo thanks
I will take your advise, Remove spark plugs and cams. Re-set cam timing with new dowel. Turn over a couple of times by hand then re-check timing. Then compression test.
If it fails the compression test, well I will save up and get the motor rebuilt.
Thanks again

[rmwood7]

Oh is there a washer for the tenshioner to stop oil leaks

[71TA22]

Yes there is. You want a 2mm thick fiber crush gasket between the tensioner and head. Make sure the head and tensioner are both clean before putting the tensioner on. Use gasket seal on both gasket faces to be sure.

The common 1mm thick orange card gaskets dont have enough crush and tend to leak. Attempted cure is to over tighten the tensioner - then one day it snaps.

[rmwood7]

Thanks Mike
Maybe that's what happened in the first place, I will let you know how I go.

[rmwood7]

Well set up the timing, replaced the dowel all lined up, new chain tensioner, turned it over by hand, CLUNK ,The timing chain seems to jump, and after a full revolution and a few clunks the chain is as slack as on the top guide.
I'm thinking stretched chain ?????

[jb_22]

Did you prime the upper tensioner by pumping it under oil & took the dizzy off to prime the oil pump? If the tensioner isn't tight then the chain will slip on the sprockets. Not necessarily the timing chain being stretched cuz I did the same thing with brand new chains - just prime the oil pump & tensioner, it should be fine