MtAdamsMack Posted December 5, 2012 Share Posted December 5, 2012 Hi I'm new to the forum. Got a real problem. Our '74 log self-loader is blowing fuel out of cylinder 4. Sooty fuel is dripping out the manifold and there's enough smoke to hide the truck from anyone behind it. At higher RPMs the engine starts popping real good. We pulled the injector and its soaking wet. Anyone seen this before or have suggestions on where to start? Hoping its not terminal. Thanks for any ideas! Will work on photos but only have dial-up out here so it takes a while... Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/ Share on other sites More sharing options...
mike69mackman Posted December 5, 2012 Share Posted December 5, 2012 If I had to guess I believe the injector is stuck open and is dumping fuel Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149514 Share on other sites More sharing options...
MtAdamsMack Posted December 5, 2012 Author Share Posted December 5, 2012 Ok. Will start there. I believe its a Bosch injector so hopefully i can find a replacement. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149516 Share on other sites More sharing options...
Lmackattack Posted December 5, 2012 Share Posted December 5, 2012 IT MAY HAVE BLOWN OFF A INJECTOR TIP...IF IT IS A BOSH INJECTOR JUST SWAP IT INTO A DIFFRENT HOLE AND FIRE IT UP. IF THE OTHER HOLE IS SPEWING ITS LIKELY THE INJECTOR. IF IT DOES NOT THEN I WOULD SAY SOMETHING IN THE PUMP... Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149524 Share on other sites More sharing options...
farmer52 Posted December 5, 2012 Share Posted December 5, 2012 IT MAY HAVE BLOWN OFF A INJECTOR TIP...IF IT IS A BOSH INJECTOR JUST SWAP IT INTO A DIFFRENT HOLE AND FIRE IT UP. IF THE OTHER HOLE IS SPEWING ITS LIKELY THE INJECTOR. IF IT DOES NOT THEN I WOULD SAY SOMETHING IN THE PUMP...Look at the tip when you pull the injector and make sure it looks okay. Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149529 Share on other sites More sharing options...
MtAdamsMack Posted December 7, 2012 Author Share Posted December 7, 2012 Ok went to swap them but now thinking we need to back up and look at the turbo first. shaft is bent and it needs to be replaced. Any leads on where to look for an old turbo? It's a Garrett 631GC4105. maybe this is a question for a separate post. Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149917 Share on other sites More sharing options...
Lmackattack Posted December 7, 2012 Share Posted December 7, 2012 When you say bent is it worn to the point that it can touch the housing or do you just feel a little free play? can you tell id any oil is leaking out the exhaust side or intake side? I put a turbo on my truck from a junk blown engine . cost me less than $50. lots of the old engines just sitting around. hard part is finding one that was not kept out in the rain with the boot off the turbo so water did not get in. Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149923 Share on other sites More sharing options...
farmer52 Posted December 7, 2012 Share Posted December 7, 2012 Turbo should not be the reason for excess fuel. Is the smoke white, blue, or black? I still would recommend pulling the injector and looking at the tip. If the tip looks okay, swap it with another cylinder and see what happens. Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149926 Share on other sites More sharing options...
MtAdamsMack Posted December 8, 2012 Author Share Posted December 8, 2012 Did look at the tip and its intact. We were going to switch injectors as suggested when we noticed the turbo probelem. The central shaft is bent so the fans on each side scrape the housing. Thinking we may have more than one problem and the turbo is the first place to start. Smoke is all colors but mostly black. Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149953 Share on other sites More sharing options...
farmer52 Posted December 8, 2012 Share Posted December 8, 2012 Black = too much fuel. And if the turbo is bad...that will make it worse (not getting enough air). Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149958 Share on other sites More sharing options...
MtAdamsMack Posted December 8, 2012 Author Share Posted December 8, 2012 Right. Thinking its over compensating with fuel because of too little air. Looked at Garrett turbos and this one is obsolete. Any thoughts on where to look around? Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149960 Share on other sites More sharing options...
Lmackattack Posted December 8, 2012 Share Posted December 8, 2012 If the shaft hits the housing then it's worn or broken bushing and seals shot. Find a new turbo before it snaps the shaft,runs away on the oil, leaves you stranded,or all of the above..black smoke is likely that you have no boost. The puff limiter needs to see about 15psi if I remember correctly to give full fuel. The limiter just delays delivery. Once it's spooled up and above 15psi your foot controls the fuel amount. If you can't build more than 15 psi or the puff is unhooked it will be dumping to much fuel with to little boost. That's where the black comes from. As for white that can be oil or poorly burned fuel. Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-149970 Share on other sites More sharing options...
Mort Posted December 8, 2012 Share Posted December 8, 2012 If the shaft is bent there would be instant disintegration. I'm thinking very worn bushes. Once it spins up probably just acceptable. Check for leaks between turbo and inlet manifold, particularly the hoses. These cause serious black smoke. Quote Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-150013 Share on other sites More sharing options...
farmer52 Posted December 8, 2012 Share Posted December 8, 2012 Oil usually causes blue smoke. Unburned fuel (or cold operation) will result in white smoke. Black smoke is caused by too much fuel or not enough air that is partially unburned (soot). Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment https://www.bigmacktrucks.com/topic/28701-help-74-rl700l-puking-fuel-from-number-4-cylinder/#findComment-150017 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.