MEP803 Fixup

[DieselAddict]

Over the weekend I got the fuel lines on one of the 803's replaced so I could load test it. Started the unit and warmed it up. It had the normal raw fuel smell the LP engines have before they warm up BUT in this case the smell only decreased some but didn't go away. Hm...

I warmed it up and put it on load and its doing fine holding the load but more smoke than normal. Maybe it is wetstacked. It has about 50hrs showing on the clock. I bring the load up and it looks like it is running on 3 cylinders. Crap.

Initial checks - no crankcase pressure (good news). Getting some puffing in the intake. Thinking we have a stuck intake valve.

Interestingly even running on 3 cylinders it will still make 10kw. It won't make 12 but it will make 10. This should be a strong runner once I get it running on all 4.

Will document the progress as I make it here.

 

[Ray70]

Interesting! Puffing / popping in the intake definitely sounds like a leaking intake valve.
If it's wet stacked I have seen many sets where a valve gets hung open just a bit due to carbon buildup on the valve/seat.
I have fixed a lot of them by removing the valve spring, pressurizing the cyl. with air and spinning the valve with a cordless drill to scrape off the carbon, then reassemble ( wait 1/2 hr. before starting to bleed down the lifters ) then start and run it hard.
Note: the air is really only so I can hear when the valve is seated correctly. if you don't have a way to pressurize through the injector hole, just put the piston at TDC and pull upward on your drill a bit and spin the valve back and forth a couple dozen times.

 

[loosegravel]

Just curious Ray. Without pressure in the combustion chamber holding the valves up, how far will they drop when the piston is at TDC? It may make it difficult to compress the springs far enough to get the keepers off of the valves.

 

[WWRD99]

Over the weekend I got the fuel lines on one of the 803's replaced so I could load test it. Started the unit and warmed it up. It had the normal raw fuel smell the LP engines have before they warm up BUT in this case the smell only decreased some but didn't go away. Hm...

I warmed it up and put it on load and its doing fine holding the load but more smoke than normal. Maybe it is wetstacked. It has about 50hrs showing on the clock. I bring the load up and it looks like it is running on 3 cylinders. Crap.

Initial checks - no crankcase pressure (good news). Getting some puffing in the intake. Thinking we have a stuck intake valve.

Interestingly even running on 3 cylinders it will still make 10kw. It won't make 12 but it will make 10. This should be a strong runner once I get it running on all 4.

Will document the progress as I make it here.

View attachment 894545

My 803 recently is starting fine but not firing on cylinder 3 and 4!! I turn in the idle knob to increase rpm and in about 10 minutes they start working...I'd be curious as to what you find. Mine is a low hour 160 as well. The valve sticking does make sense because it does smoke a good bit and the exhaust manifolds are cold on 3 4 while 1 & 2 are at 170 or so. I may try some oil additive and see if it clears up. I did not load mine while the 3 & 4 were not working. Once they did I ran it under load for almost a day.

 

[Ray70]

At TDC the valve can barely move at all, so it shouldn't be a problem getting the keepers out. If he has a problem you can always get in there with something to hold the valve up, or even stick some string or thin rope into the cylinder, then rotate the crank by hand to push the rope up and against the valves.

 

[loosegravel]

Neat trick! From someone who’s speaking from experience for sure

 

[DieselAddict]

At TDC the valve can barely move at all, so it shouldn't be a problem getting the keepers out. If he has a problem you can always get in there with something to hold the valve up, or even stick some string or thin rope into the cylinder, then rotate the crank by hand to push the rope up and against the valves.

We used to put string in the cylinder through the plug hole on a gas engine to hold the valves up when we needed to change valve springs trackside.

 

[DieselAddict]

Well, I think I found the problem with the cold cylinder.

Bent pushrod. Looks like a snake. Inside of the engine is pristine.

Swapped in a good pushrod and waited till the lifter bleed down.

She fired up on all 4 cylinders. Running SMOOOOOTH and got heat across the exhaust manifold.

Put it on load after it warmed up and 12kw didn't even pull it down to 60hz from a 61.5hz unloaded RPM. She is going to be a beast.

Going to change the oil and pull the side cover to see how bad the lifter is beat up. I expect it is going to look rough if the end of the pushrod is any indicator. I do have oil coming through the replaced pushrod as normal. Thats a good sign at least.

One step closer to having it ready to go to its new home.

 

[Guyfang]

A few taps with a hammer, be good as new!

 

[DieselAddict]

Quick question for the brain trust. I pulled parts from one of the parts units to finish up the 803. The parts machines are 90s vintage. The 803 I'm working on in this thread is early 2000's. The rocker arms are the same size with one difference. The newer vintage machine has an oil hole for the pushrod where the 90s vintage machines do not. I'd prefer to not mix the styles.

Anyone know when this change was made?

If anyone has one of the newer rocker arms available drop me a DM. I'd rather source one from the community here than a random person on ebay.

 

[DieselAddict]

I see the part number difference in the manual. The two styles is 750-11280 or 750-12500.

Now to find one.

 

[Guyfang]

You have the Lister Peter Manuals? Might be in there.

 

[DieselAddict]

Yea, I looked it up. Just being lazy.

 

[Guyfang]

Should not make a difference. As far as I know, the NSN for the engine never changed. And had there been some kind of change big enough to make a difference in the rocker arms, the engine NSN would have changed.