Engine Blow-by

[Mack B Mike]

Hey All, more troubles again, now i got the issues worked out with the rear, which is working perfect something else had to happen, took the truck out for a ride a few days ago after about 20 miles i was going up a relatively large hill, engine almost at governed speed ~2kRPM the cab started to fill up with smoke not exhaust though, i nursed it back to my garage with a large cloud of smoke following me found smoke comming out of every possible opening to the crankcase; breather, oil fill in the valve cover and the road draft tube, small amount of oil at the breather filter and none at the draft tube, this engine did have a small amout of blowby since i have owned it but this is just insane with the oil cap off engine running the smoke would just billow out, engine temp ~ 160ºF oil pressure was 20 lbs@ idle and ~60@ governed speed hot, the engine starts in ~ 5 seconds of cranking when air temp is ~25º at 1/4 throttle no ether and almost the instant i hit the air valve when hot, i let the truck sit for a few hrs and ran it again, about 5 miles down the road started doing it again, let me know if yall got any ideas,

any help would be appreciated

thx

Mike

[marvgarr]

the road draft tube might be clogged had that happen on a endt673 but it was pushing oil out the rear seal found out the road draft tube was plugged after cleaning it never leaked again

[HK Trucking]

You burned a piston.

[Mack B Mike]

You burned a piston.

that was one of my thoughts actually thought one had cracked gonna pull the heads off next weekend and check it out

thx

Mike

[HK Trucking]

that was one of my thoughts actually thought one had cracked gonna pull the heads off next weekend and check it out

thx

Mike

Sometimes they burn down the side and into the ring grooves, so you may not see too much by just looking at the piston tops, had a 673 in a B81 do just that, back in 1981.

Before you tear the heads off, try to determine which cylinder is weak due to the lack of full compression.

Loosen off 1 injector line at a time while it's idling and see which one makes the least difference in the sound of the engine, then you'll have a clue as to which piston to pull out and inspect if nothing is apparent on the top.

[theakerstwo]

Let it set for a day and crack the oil pan plug and look for coolant. If it has collant in the oil it will turn to steam and blow out the vent and look like blow/by. see it mant times but also could be a cracked or broke piston. If it had a scrouded piston it would have a wack wack noise in the mid of engine and that is what some thing is a rod brg bad. glenn

[de37champ]

Good info guys, i hate to tell someone all of the above because it always brings back bad memories to me, but very good information on what to look for, it just gives me a sick feeling to see any of the above

[MidniteMechanic]

That amount of 'smoke' i'd lean toward coolant leaking into the crankcase. Do like Glenn said and crack the pan plug. Brian

[PedroR]

im with the rest of these guys, what kind of motor is it? i would pull the exaust manifold out and look for oil in one of the cylinders

[Mack B Mike]

im with the rest of these guys, what kind of motor is it? i would pull the exaust manifold out and look for oil in one of the cylinders

hey all engine is a ENDL 673, im gonna check all the easier stuff prior to pulling it apart i dont feel that it would be a coolant issue because of the smell of the smoke, antifreeze has a distinct smell when it is heated and the smoke dont smell like that plus the oil is normal color if there was coolant in it, it would be circulated by the oil pump and make the oil look like a chocolate milkshake, but i will check all the ideas that everyone has offered, i also was reading about the head gaskets and if the head gasket is leaking at an oil galley the combustion pressure/exhaust could virtually get forced back down to the crankcase which would cause some blow by, but to the extent that this one does im going to assume the worst, the engine does have some oil seepage where the heads meet the block, thanks everyone for the imput, ill keep everyone updated with the progress, plus if i have to pull it apart it will force me to clean everything and paint it up nice before reassembly

thanks all

Mike

[fjh]

hey all engine is a ENDL 673, im gonna check all the easier stuff prior to pulling it apart i dont feel that it would be a coolant issue because of the smell of the smoke, antifreeze has a distinct smell when it is heated and the smoke dont smell like that plus the oil is normal color if there was coolant in it, it would be circulated by the oil pump and make the oil look like a chocolate milkshake, but i will check all the ideas that everyone has offered, i also was reading about the head gaskets and if the head gasket is leaking at an oil galley the combustion pressure/exhaust could virtually get forced back down to the crankcase which would cause some blow by, but to the extent that this one does im going to assume the worst, the engine does have some oil seepage where the heads meet the block, thanks everyone for the imput, ill keep everyone updated with the progress, plus if i have to pull it apart it will force me to clean everything and paint it up nice before reassembly

thanks all

Mike

do keep us updated!

If you have one bad hole the blow by would puff back at you at the fill tube!

If its a steady pume you may have another issue!If the engine is turboed it can be the turbo!

I would check Glens theroy first if its asteady plume, a simple check!crack the drain plug in the morning see what ya see!

[MACKS]

I had the same problem many years back,pulled the heads and the first thing I saw was small peices of rings imbeded in the top of one piston,you know the rest of the story.

[Mack B Mike]

do keep us updated!

If you have one bad hole the blow by would puff back at you at the fill tube!

If its a steady pume you may have another issue!If the engine is turboed it can be the turbo!

I would check Glens theroy first if its asteady plume, a simple check!crack the drain plug in the morning see what ya see!

hey all, opened the drain plug in the pan after work today, no coolant present, oil came out, was hoping this was the issue, of course not, i did run the engine for a bit, to check the smoke out again, took a while its a whopping 16ºF up here, i did notice a billow of smoke on combustion strokes comming out of the oil fill cap in the valve cover not a steady stream and also noticed that the exhaust manifold was not as hot at #4 cylinder as the remainder of the cylinders im going to assume that this is the trouble one, i will open the injector lines at each cylinder to make sure that it is #4 as HK trucking had suggested as well,

thanks everyone for the help and ideas

Mike

[fjh]

hey all, opened the drain plug in the pan after work today, no coolant present, oil came out, was hoping this was the issue, of course not, i did run the engine for a bit, to check the smoke out again, took a while its a whopping 16ºF up here, i did notice a billow of smoke on combustion strokes comming out of the oil fill cap in the valve cover not a steady stream and also noticed that the exhaust manifold was not as hot at #4 cylinder as the remainder of the cylinders im going to assume that this is the trouble one, i will open the injector lines at each cylinder to make sure that it is #4 as HK trucking had suggested as well,

thanks everyone for the help and ideas

Mike

Youll likly nailed it with the injection line thing but remove the exhast manifold will likly confirm a wet hole!

[Mack B Mike]

Youll likly nailed it with the injection line thing but remove the exhast manifold will likly confirm a wet hole!

Hey all, pulled engine apart today found more than one issue, ran engine with the fenders off to get a better look before dissassembly, found the rear head gasket leaking blowing oil bubbles out where the head meets the block, pulled intake, ex, and heads, found that the #2 cylinder sleeve had a large crack almost the whole length of the sleeve, pulled piston and found a large chunk below the top compression ring was missing, also found that there are two different style heads on the engine the front head had 5/8" corner studs and the rear head has 3/4" corner studs. On a positive note, found that the bottom end was gone over some what recently the bearings look great, no scratches or copper showing through the babbet

[Rob]

Man that just blows. Having the incorrect head on there will not let it retain a seal for a good long time I would think. That liner appears to have a fire ring so you should be able to get replacement parts readily through federal-mogul possibly.

At this point it may be prudent to look for a later model 237 for replacement as opposed to rebuilding your original.

Rob

[fjh]

Hey all, pulled engine apart today found more than one issue, ran engine with the fenders off to get a better look before dissassembly, found the rear head gasket leaking blowing oil bubbles out where the head meets the block, pulled intake, ex, and heads, found that the #2 cylinder sleeve had a large crack almost the whole length of the sleeve, pulled piston and found a large chunk below the top compression ring was missing, also found that there are two different style heads on the engine the front head had 5/8" corner studs and the rear head has 3/4" corner studs. On a positive note, found that the bottom end was gone over some what recently the bearings look great, no scratches or copper showing through the babbet

What ever ya do don't reuse the injectors with out having em tested that likly caused the failure!

also check the injector hole for 2 washers!

[Mack B Mike]

What ever ya do don't reuse the injectors with out having em tested that likly caused the failure!

also check the injector hole for 2 washers!

update on the 673

cleaned and measured block today and found that the # 2 cylinder was bored ~ .030 over, assuming std bore being 5.0945 compared to the measurement of the #2 cyl being 5.1240, when this hole was bored whoever did the engine work put a std size sleeve in, they did not put a oversized sleeve in it which is most likely why it cracked, maximum clearance between block and sleeve should be .002 to achieve sufficient heat transfer and support, i think .030 is a bit out of tolerance. new correct size sleeve is on its way.

Mike

[Rob]

update on the 673

cleaned and measured block today and found that the # 2 cylinder was bored ~ .030 over, assuming std bore being 5.0945 compared to the measurement of the #2 cyl being 5.1240, when this hole was bored whoever did the engine work put a std size sleeve in, they did not put a oversized sleeve in it which is most likely why it cracked, maximum clearance between block and sleeve should be .002 to achieve sufficient heat transfer and support, i think .030 is a bit out of tolerance. new correct size sleeve is on its way.

Mike

Is the bore still round in the block?

Rob

[theakerstwo]

Is the bore still round in the block?

Rob

No not on a engine that old. But it should be. If it ant maybe he can find some of them out of round rings.

[Mack B Mike]

No not on a engine that old. But it should be. If it ant maybe he can find some of them out of round rings.

Hey All,

actually it was suprisingly round within .0015 - .002, checked top, middle and bottom of the bore 3,6,9 and 12 o'clock at all the positions after cleaning, the #2 cylinder was the only one that was bored .030 over, i think whoever overhauled the engine prior to me stuck the wrong sleeve in, thats the only think i can think of

[Rob]

Hey All,

actually it was suprisingly round within .0015 - .002, checked top, middle and bottom of the bore 3,6,9 and 12 o'clock at all the positions after cleaning, the #2 cylinder was the only one that was bored .030 over, i think whoever overhauled the engine prior to me stuck the wrong sleeve in, thats the only think i can think of

I'm not much of a mechanic so don't know why someone would only bore one sleeve bore, then not be able to tell, (by feel) the excessive clearance of using a standard sleeve. The sleeve would slide into the bore much too easily.

Sure hope you get it back to where it needs to be.

Rob

[fjh]

I'm not much of a mechanic so don't know why someone would only bore one sleeve bore, then not be able to tell, (by feel) the excessive clearance of using a standard sleeve. The sleeve would slide into the bore much too easily.

Sure hope you get it back to where it needs to be.

Rob

It is quite common to bore one hole I beleive there were actualy 2 thou over liners avalible at one time and you could hone the hole out to fit em if the liner slid in to easy.

[theakerstwo]

It is quite common to bore one hole I beleive there were actualy 2 thou over liners avalible at one time and you could hone the hole out to fit em if the liner slid in to easy.

Back in the mid 60s we used dry ice and put a .001 srink fit in the liners and then some times you had to hone them to get the piston clearance and then in most cases that caused the rings to seat slow if ever so one day Mack factory said this is silly so we will stop the srinking to put them in and i think that help alot. I know they were alot more easy to get out.

[HK Trucking]

Back in the mid 60s we used dry ice and put a .001 srink fit in the liners and then some times you had to hone them to get the piston clearance and then in most cases that caused the rings to seat slow if ever so one day Mack factory said this is silly so we will stop the srinking to put them in and i think that help alot. I know they were alot more easy to get out.

Glenn, did you ever have fun getting the liners out of the rear holes on a DM or U model ?

A couple times I had to push from the bottom because my half assed sleeve puller wouldn't fit under the dashboard, and actually had the front of the truck off the floor before the liner suddenly came loose. Also welded on the inside of a few to shrink 'em when they wouldn't come out.

.