Caution removing freeze/core plugs Multifuel Engine

[ENCS_DEI]

FYI, recently got a M35A2 that was experiencing blowby with just over 1000 hrs on the engine. I found that No. 1 cylinder sleeve was scored along the front of the engine along the axis of the piston pin. After disassembly I found a bright mark on outside of sleeve and a raised dimple in the cylinder bore at corresponding location. Cause was improper removal of freeze plug during last overhaul. There is not enough clearance behind the left side of the freeze plug (as viewed from front of engine) and sleeve bore to drive the plug out with a punch. The TM gives procedure for removal but if your going to knock them out with a punch the front plug and rear plugs "MUST" be carefully driven out from the right side (as viewed from front of engine).

 

[Recovry4x4]

Wow, great info! I'd never have even thought of that!

 

[CCATLETT1984]

jeeze, they must have kept wailing on that thing even after it stopped moving.

i had the opposite issue, the freeze plug dropped in to the block passages, boy was that fun getting out.

 

[WillWagner]

Well, look at that! Seen that on a Cummins B. But they are a parent bore block...no liners. Ended up putting a sleeve in it. That's the one behind the WP? Where are you getting a cylinder kit or liner/rings, and how much are they gonna set you back. Great pics!

 

[ENCS_DEI]

I am getting a power pack from White Owl @ $220. While going through the engine I also found all sleeves cracked from the flange running down @ $95 per. I am currently tring to get 5 ring sets NSN 2815-01-454-6145 which are for the 3 ring piston which is apparently uncommon. If I have to go to an updated 4 ring piston configuration it's going to set me back X6.

 

[WillWagner]

OUCH! Well, take lots of pics. It's nice to see the inside of one of these beasts. If you put bearings in it, save the old ones. Maybe Bjorn can use them. He's got a knock goin' on in one of his trucks.

 

[OPCOM]

What an unpleasant problem to find! good thing you found it before something broke and not only ruined the engine but destroyed the evidence.

 

[cranetruck]

Good procedure is always interesting to read. Thanks Russ!

How did you determine that the blowby was out of the ordinary?

PS. Did you get your flasher problem solved?

 

[clinto]

Thanks for posting this.

This is the kind of experience you can only get from turning wrenches. No matter how many times you read the TM, it's the real world experience that separates a "I can do this" guy from a "I know what I am doing" guy.

 

[surpdlr]

If you put bearings in it, save the old ones. Maybe Bjorn can use them. He's got a knock goin' on in one of his trucks.

If you need NOS standard main bearings for the Multi fuel, Front Line Military Vehicles has them in stock at a very reasonable price (not allowed to say the price, as that is advertising and my last post was removed).

 

[cranetruck]

Thanks Jeff!
Will keeps reminding me about the knock and I'm getting close to doing something about it (the knock, that is ).

Images of freeze plugs on my parts engine....

 

[ENCS_DEI]

As far as the blowby, the engine would emit light smoke from the crankcase breather tube, when I put my hand over the tube it was really trying to push it off. I didn't need a manometer to tell. it would probably have blown the water right out of a U tube.

I could never find what crankcase pressure should be while searchng the TM's. My best guess would be that anything below 3-4" water would indicate tight engine.

Russ

 

[rlp094]

Good to know, will be doing this job soon!

 

[Floridianson]

Good to know, will be doing this job soon!

It's good to see the new Recruit's digging.

 

[Wildchild467]

I have some questions on your build.

-Were you able to find replacement piston rings for these style pistons (with 2 compression rings and one oil ring)?
-How did your truck run with these pistons? Did you experience any blowby at all after you put it together with the new style pistons?

Thank you.