Jona$
Master
Up and running with good oilpressure , now for powdercoating
Jona$
Master
And down again.. The sled have had several starts and reved it, tried launchcontroll and checked timing again.. all good+oil. then it been sitting for a while before i got the skid in and lined up the track, therefore i started her up and let her idle to warm and hit the throttle so track would go aorund, when i let go off the throttle it stopped, and it lacks compression again.. i bet money its another bent valve.
This is what have happend.
Engine out presummer because of leaky coolant hoose, assembled and fired up sled and it hit a valve when revved up, changed it and put i together again, this time with the display connected and got low oil pressure and she shut off. another bent valve and we realized there was a airbubble in the system preventing the valve to open and give the engine its lubrication.
Fixed it and got the oil flowing before starting her up, checked the bleedscrew at the back and oil came, and at the return.. let her idle to she got real warm and tested launchcontroll, made several starts from cold to warm.. no problem..
Now a few weeks later the rear skid got back in and i fired her up to align the track. let her idle to the point she got warm and applyed throttle so the track went around, and just when i let go she shut off.. another valve i pressume since i seem to lack compression again.
What can it be , i have taken the chaintensioner apart so its possible the spring has wrong pressure.. but how can it then hold several starts with launchcontroll etc.. and a few weeks later die from a simple rev to get the track moving?
Im 100% the timing were right all of the 3 times, and shims were dialed correctly.
What should i look for, could the tensioner back of maybee?
how do you replace the camchain.. etc etc
This is what have happend.
Engine out presummer because of leaky coolant hoose, assembled and fired up sled and it hit a valve when revved up, changed it and put i together again, this time with the display connected and got low oil pressure and she shut off. another bent valve and we realized there was a airbubble in the system preventing the valve to open and give the engine its lubrication.
Fixed it and got the oil flowing before starting her up, checked the bleedscrew at the back and oil came, and at the return.. let her idle to she got real warm and tested launchcontroll, made several starts from cold to warm.. no problem..
Now a few weeks later the rear skid got back in and i fired her up to align the track. let her idle to the point she got warm and applyed throttle so the track went around, and just when i let go she shut off.. another valve i pressume since i seem to lack compression again.
What can it be , i have taken the chaintensioner apart so its possible the spring has wrong pressure.. but how can it then hold several starts with launchcontroll etc.. and a few weeks later die from a simple rev to get the track moving?
Im 100% the timing were right all of the 3 times, and shims were dialed correctly.
What should i look for, could the tensioner back of maybee?
how do you replace the camchain.. etc etc
machzrobbie
Expert
The only time I've seen timing chain jump when the motor is running is because the cams sieze becaus of lack of oil - they will sieze in about 10 seconds with out lube(been there done that) and you said it shut down because of no oil pressure - did you check to be sure the cams turned freeely?- before you fire the motor you have to be sure that oil pump is pumping oil. If you start the motor even for a second without oil, damage has already been done and its just a matter of time before cams sieze. Check to be sure you cams will turn freely in the head with all the valves removed - you should be able to turn with your fingers.
Jona$
Master
Well thats the case, this third time i checked that it put up oil by just cranking the starter and checking for return of oil the resvoir? then i fired it up and checked the little bolt at the back and it spewed out oil when removed.. i started it alot of times since then and no problem with the oil.
Its been sitting since then a few week, a couple of days in a steep angle with the front pointing down. This time i didnt check anything since it worked 5-6time i tried it at days between. And sure it fired up and then rest is history... i checked that the oilreturn after it happend by cranking the starter and yep, the oil flows back.
Its been sitting since then a few week, a couple of days in a steep angle with the front pointing down. This time i didnt check anything since it worked 5-6time i tried it at days between. And sure it fired up and then rest is history... i checked that the oilreturn after it happend by cranking the starter and yep, the oil flows back.
machzrobbie
Expert
there's two pumps in one, in the oil pump - one pumps oil out of the bottom of the motor, and sends it back to the oil tank and one lube's the motor. So just because oil is going back to the oil tank doesn't mean oil is going through out the motor, its just pumping what is in the bottom of the motor to the tank. You have to be sure there is oil coming out of the little hole in the head beside the exhaust port when cranking. My other concern is that is the cam siezed previously. Did you do anything to repair the cam jounals in the head from running it without pressure before?. The cams actually "float" in oil when the motor is running and there is not supposed to be any contact between cam and the jounal - if they siezed previous and there is any drag or metal to metal contact it will just continue to get worse and you will continue to have the same problem (sounds like what's happening)
Jona$
Master
thats what im afraid of, so im gonna remove the head and give it to engine builder here in town to check head and cams so they hold up the specs.
And no i could not see any metal contact etc from the outer journal, but at cyl 4 the intake cam had grinded out a bit so i needed to use a dremel to get the valve head out, this was the first time it seized.
Do you know how to remove the lower sprocket gear, i suppose it needs to be removed so the camchain can be replaced? and should i go manual or new oem cam chain tensioner.
BTW could i realy get oil out of the hole at the exaust just by cranking the starter, isnt that "to slow" rpm?
And no i could not see any metal contact etc from the outer journal, but at cyl 4 the intake cam had grinded out a bit so i needed to use a dremel to get the valve head out, this was the first time it seized.
Do you know how to remove the lower sprocket gear, i suppose it needs to be removed so the camchain can be replaced? and should i go manual or new oem cam chain tensioner.
BTW could i realy get oil out of the hole at the exaust just by cranking the starter, isnt that "to slow" rpm?
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machzrobbie
Expert
I've never tried to change the chain without splitting the motor - and I'm pretty sure you're going to half too. There's nothing wrong with the stock tensioner, a manuel one will work as well, you'll just have to be sure its stays tensnioned. Yes you can get out out the bleeder and can actually see it come around the camshaft while cranking. You're not the first and won't be the last to expeirence this - I use a bit of air pressure on a oil tank to get the lube pump to pick up prime.
rxrider
Jan-Ove Pedersen
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You need to take the motor apart to change the cam Chain.
One more thing, make sure the cam in question is straight, if you have run-out on the cam it will seize.
Your cam may have been damaged when it killed Your valves.
One more thing, make sure the cam in question is straight, if you have run-out on the cam it will seize.
Your cam may have been damaged when it killed Your valves.
machzrobbie
Expert
Great advice - bottom line - measure and check everything on that head before it goes back together - you don't want to do this again!!
Jona$
Master
Oh really, that bad. Well then the chain stays and tensioner gets replaced. As for what both rxrider and mazhrobbie says is just in the range of my feelings.
The only thing you guys may know? is why did it start several runs with days between were i allways let it idle to warm and once tried the launchcontroll and one other with higher rev and one with alot quick on and off. Why didnt it seize up then.
Im gonna check the bolt at the exhaust when i start the tear dówn, but it worked everytime i tried it before i put the rest together.
I had may share of problems, thats for sure.
The only thing you guys may know? is why did it start several runs with days between were i allways let it idle to warm and once tried the launchcontroll and one other with higher rev and one with alot quick on and off. Why didnt it seize up then.
Im gonna check the bolt at the exhaust when i start the tear dówn, but it worked everytime i tried it before i put the rest together.
I had may share of problems, thats for sure.
Jona$
Master
Also if anyone have diagram with all spec on what need to be messured on the head and the cams. valves?
Jona$
Master
As for now im getting the head back tomorrow, and one thing was for sure. The inner and outer journal were to tight, i guess from heating when runned without oil?
Hopefully a little grinding and new intake valves and im game again.. well se tomorrow.
Hopefully a little grinding and new intake valves and im game again.. well se tomorrow.
