7.3 cam timing

[71cc]

I posted this on another forum and haven't recieved any input so far. So I will ask you guys.

I have a reman 7.3 I bought for a project truck.The story is that it quit running and the previous owners couldn't get it to start again.It had a new lift pump,glows,fuel filters, and starter.I figured it was ran out of fuel and they couldn't get it bled out again.I don't know how many miles it has on it since the rebuild,but it looks to have been run awhile.So I look at everything and try to crank it.It sounds odd when cranking over.There seems to be a lot of reversion in the intake so I suspect a bent/stuck valve. I pulled the exhaust manifolds and spin it over. Every cylinder puffs an exhaust stroke, then will suck your hand tight to the exhaust port.All cylinders do this.It is like the cam timing is slow.The motor doesn't seem to pump much air through it.I pulled a valve cover and watch.Everything looks, and moves fine. Is there a way to verify cam timing without pulling the front off the motor? I even tried cranking with a little ether and it never tried to run. I unfortunately do not have a way to test compression.I suspect a loose or possibly sheared crank key. Any ideas ? There are no other indications of damage, visually or by sound.

 

[towcat]

I posted this on another forum and haven't recieved any input so far. So I will ask you guys.

I have a reman 7.3 I bought for a project truck.The story is that it quit running and the previous owners couldn't get it to start again.It had a new lift pump,glows,fuel filters, and starter.I figured it was ran out of fuel and they couldn't get it bled out again.I don't know how many miles it has on it since the rebuild,but it looks to have been run awhile.So I look at everything and try to crank it.It sounds odd when cranking over.There seems to be a lot of reversion in the intake so I suspect a bent/stuck valve. I pulled the exhaust manifolds and spin it over. Every cylinder puffs an exhaust stroke, then will suck your hand tight to the exhaust port.All cylinders do this.It is like the cam timing is slow.The motor doesn't seem to pump much air through it.I pulled a valve cover and watch.Everything looks, and moves fine. Is there a way to verify cam timing without pulling the front off the motor? I even tried cranking with a little ether and it never tried to run. I unfortunately do not have a way to test compression.I suspect a loose or possibly sheared crank key. Any ideas ? There are no other indications of damage, visually or by sound.

welcome to the site
can you tear off the front cover?
if not, you can try a quick and dirty check of the timing by setting the crank up at TDC and pulling the injection pump drive cover and check to see where the locating pin is positioned. it should be at the 4'oclock position with the access cover removed.
post your findings if you can take pics that would be way cool

 

[hesutton]

Also welcome to the site. Did the engine never run correctly after the work was done? If the lift pump getting fuel to the fuel filter? You can check by opening the schraider valve on the filter head while someone is cranking it over for you. The reason I ask is.......if the lift pump was intalled incorrectly, the arm will/can be broken off and fall down into the pan. No fuel equals no start....but that doesn't explain the vaccum at the exhasut ports.

I'm afraid you need to remove the front cover and see if the timing marks on the gears line up or not.

Please let up know what you find and photos if you can.

Heath

 

[71cc]

The story on the motor comes second or third hand, so that is why I started inspecting everything. Most people not familiar with diesels would be at a loss to bleed the air out of one once ran empty.Whatever the cause, the person that had the truck gave up on it and sold it to the wrecking yard.I only gave $300 for the dressed engine. Everything i have inspected looks great. As far as the lift pump, I removed it, looked fine. I am going with an electric pump. I don't have fuel plumbed just yet.I only wanted to see if it would even crank on ether.It never hinted at combustion.It just doesn't seem right. I honestly doubt it can run like it is, it is moving air in and out instead of through the motor..There are no mechanical sounds or apparent damage anywhere I have found.Everything seems to have proper range of motion in the valvetrain.The engine is sitting in a bare chassis right now so disassembly is not that big of an issue.I wanted to get it to at least run for a few seconds before I plumb water to it.I need to hear it run for an extended period of time to decide what shape it is in.If it would at least hit on ether I would bleed out the fuel system and try starting it. I am afraid to with valve train timing questionable.If something is sheared it could possibly destruct a salvagable motor.BTW i am on the for truck site as well.This is going in my 72 ford crewcab.Thanks for any ideas.

 

[71cc]

welcome to the site
can you tear off the front cover?
if not, you can try a quick and dirty check of the timing by setting the crank up at TDC and pulling the injection pump drive cover and check to see where the locating pin is positioned. it should be at the 4'oclock position with the access cover removed.
post your findings if you can take pics that would be way cool

What exactly references to the mark on the damper for a TDC ? I see the two "probe" pickups.. While the quick method on the IP gear sounds good, I suspect a cam timing of a few degrees could cause these symptoms and not be detectable by eye. Also if it is shearing the key it is possible that it is still close enough not to have crashed the valves into the pistons.I guess I will pull the fron end off to eliminate or confirm this before going further.I would kick myself if it "was" a good motor and I finished it off.

 

[towcat]

take a minute and clean the crud off the timing tab and you'll find the TDC mark. it should be at the centerline to the upper probe.
if anything has slipped, the pump drive locator will not be where it's at in the pic i posted earlier. in this situation, you are either dead on or way off.
to answer your latest question, any variance in the timing will cause contact with the pistons and valves. the timing between the two is very tight.

 

[typ4]

If the oil relief stuck it is possible that the lifters pumped up and you had some piston to valve love. Also if someone over revved it, it can also bend valves. If it is in time and has bent valves DO NOT get it running with the injector pump that is on it, it could be bad and you could have a runaway.

 

[71cc]

Here is the current diagnoses.

I decided to pull the front end down to verify.Everything was in time.Keyway looked fine. So I started digging deeper. I pulled the intake manifold and spun the engine. Several cylinders were spittting back into the intake port. It sounded like a blown head gasket at first.I pulled both valve covers and all is ok. Valley looks great, everything in order there.I fogged a little penetrate into the intake to wet the valve,also sprayed down the stems from the top side. When it built up oil pressure and worked everything through range of travel it started sounding like it should.The reversion stopped and sounded healthy.I suspect the valves were sticky from setting so long and or there was trash under the seat area.I am going to do a little cleaning and repaint and re-assemble. I am sure it will run now.Everything in this motor I have looked at is in beautiful shape.The coolant passages are pristine.I wasn;t going to be satisfied until I verified all is well.It was worth the trouble for the peace of mind.BTW there was no wetness anywhere to indicate oil consumption past the valves.Thanks for everyones input.

 

[typ4]

I did not realize it had been sitting a long time, you may have an awesome engine there. The lifters being bled down will change valve action/ timing drastically. And will also cause what you were describing, reversion is a good description. Now do a compression test ,although you may still have some leakage if there is rust bits on the valve seats.
Good Luck

 

[OLDBULL8]

The lifters being bled down will change valve action/ timing drastically.QUOTE]

In thought all these diesel engines have solid/roller lifters ? Am I wrong thinking that ?

 

[Agnem]

Hydraulic roller lifters.

 

[RLDSL]

take a minute and clean the crud off the timing tab and you'll find the TDC mark. it should be at the centerline to the upper probe.
if anything has slipped, the pump drive locator will not be where it's at in the pic i posted earlier. in this situation, you are either dead on or way off.
to answer your latest question, any variance in the timing will cause contact with the pistons and valves. the timing between the two is very tight.

Hey Calvin, I believe you meant to say that the TDC is in the centerline of the lower probe hole

 

[icanfixall]

True... The lifters are roller needle bearing rollers but... I have a set of bushing roller lifters. the part number is Melling JB-2104 & made in the U.S.A... And I don't mean USA Japan..... There is a town named that so they can print on everything.... Made in USA and get away with it being made in Japan. I really have never seen or heard of the bushing type lifters being oem inany motors either.... Anybody have information on this???

 

[towcat]

Hey Calvin, I believe you meant to say that the TDC is in the centerline of the lower probe hole

you're prolly right. my memory is getting pretty bad these days.

 

[seawalkersee]

I think I have a lifter or two that are crap too. When I first got it, it was making the popping noise through the intake. Sounds like beating on a bucket with a rubber mallet right? When I threw a new set ofinjectors in it, it sat for a week and it would make the sound again. It realllllly clacks at higher rpms. I new a new set.

SWS