Cracked Engine Block

I got an old diesel engine that i actualy never used for anything.
its a 4 liter 50 hp 4 cyl water cooled engine, don't ven remember when it got into the yard.
I will need it to power a stationary chipper.


Now, when i got ahold of it, i seen that the block did got freeze once in its life, the welding is visible on the block.
No big deal.

Today i sortha found some spare time to play with it,
changed the oil, added a battery.
I started to fill her up with water, nothing extra here.

But after starting the engine, i noticed water comming from the darn block.
The flow is significant actualy.

I do not think we left any water in it, the radiator was empty for sure.
Not so sure about the block it self, then again the hole where water is flowing from is verry tiny. And its a single hole, for a "proper" froozen block its used to be a longer crack.
The engine started well, actualy i was surprised how easy was it.


Now, the question is, can it happen that only the welding was bad at a single point?
Or if we want to fix it, do we have to take everything apart, and check if the inside wall of the block is cracked too?

I was hoping the engine is in working order more or less, so i do not have to tie down a tractor for this task.
A big repair job would not worth it.


How would be the least time/energy consuming to tell if only the outside of the block is cracked?
If so, would epoxy do the trick to "patch" that small hole ?

Crack or a hole? The difference is important as a crack will, in time, spread. The safest way would be to drill out the 'hole' and tap/plug it. This way there is less likelihood of any crack migrating.

it is not larger than 1-2 milimeters. Not sure if its a hole or a crack.
Did nt investicate it that deep yet, sadly i had no time left for it..
question is how will i tell if the "internal" or.. "cylinder side" is damaged or not whitout taking the whole thing apart...

As for fixing the leakage one epoxy glue i have has 170 kg/cm^2 force, and is resistant to heat up to 120 celsius degree. Was thinking of simply using that. I used it to glue castings, but never a motorblock -yet:) -

Indeed. It's also best to drill a small hole at all ends of cracks before repairing. Stress relief and all that.

Your leak could simply be a bad spot in the weld, but hopefully it was done by someone with cast experience and proper rods.

Otherwise, JB-weld may be your friend...

well looking at it, i think the weld was not realy done in a professional manner.

oh well 2 small holes and a bit of epoxy is not a big deal.
still bugs me where will i know if the other side of the block is damaged or not. Would not like coolant sneaking into the cylinder area.

Anything getting into a cylinder will generally wind up in the bottom of the oil pan after it sits overnight. Crack the drain plug and see if any coolant (which is heavier than oil) runs out.

Also watch for milky-looking oil on the dipstick, which indicates there is oil/water trying to mix with the engine running.

If you use epoxy/etc. for a patch, make sure to grind/sand the area down to bare metal first. Sandblasting is ideal.

another method is to do a leak down test, they sell adapters to thread in place of a spark plug or glow plug. fill the system with water and pressurize the cylinders one at a time. look for bubbles at the rad cap, or take notice if the flow out of the hole increases with air pressure.

^ You can also check for radiator bubbles with the engine running, but freeze cracks are often below the compression area (from not draining the block properly).

if you have sleeved cylinders ... you may have just got lucky .
no telling today , but many years ago sleeved/diesel went together .

i would not worry about the inside of the crack .
Jb weld is ok in a pinch ... as in 75 miles from nowhere , back in the mountains in northwest montana (ask me how i know) .
for a real fix ... take it to someone who knows what they are doing ...
the first clue will be when they use a rosebud to heat the area prior to welding and after they are done will play the flame on it for a bit and then throw an insulating blanket on it and tell you to come back tomorrow .

like mack and others said , you will know if there are internal problems rather quickly .
if you are sucking water into a cylinder (even a small amount) it will show on the exhaust ... it will be white or whitish ... just like starting cold diesel with low compression/a bad injector on a cylinder .

oh yeah ... put some anti-freeze in it .
it really helps keep metal from crudding up .

it is sleeved, all russian diesels are.

sadly this engine has no glowplugs or spark plugs.
starting relays purely on a 3 Kw rated electric starter and a de-compression valve.

come to think of it, the engine does run. I would suspect if the sleeve is damaged it would not be able to turn at all.

where i found the hole, the water is gushing. if the crack was present on the cylinder side too, should not it have an oscillating nature visible at low RPM ? I.E. when the cylinder fires the gushing would be boosted, no ?

should we still drill the little crack if we use JB weld, or grinding down to clean metal is okay ?

it is best to remove as much contamination from the area as possible ... this includes grease , oils and (obviously) oxide based crud .
the pinholes may be indicative of porosity in the weld ... grind it back a little with a small wheel or file .

look closely at the repaired area (both sides) ... as was stated above , and because you do not know who did what , it is possible that the crack was not drilled at the ends to prevent "stress running" .

to my notion , jbweld is at best a temporary fix that will fail about the third time you turn your back on it .
if you want to eliminate a headache in the making ... weld it up properly .
this is cheap insurance .

about sleeves ...
i have not seen many sleeves that were cracked by freezing .
about the only sure way is to tear the engine down and inspect the sleeves in situ .

a damaged sleeve may not prevent an engine from "turning over" or running (per se) ... it may sound like the pistons are swapping holes but it may still run .
it all depends on the nature and extent of the damage .
a "lope" in the sound of the engine running is indicative of *something* wrong .

for example ... a '72 john deere tractor with a four lung diesel :
it ran flawlessly since it was new ... the guy ran it for 30 years .
it had never been subject to coolant freezing (we from the areas where -40F is not uncommon protect against this as a matter of wrote) .
over a period of time it seemed that the engine was "acting funny" and got progressively worse ... not rapid major changes in performance but slow .
we talked about it but chalked it up to 30 years running and imagining things .

i was away on a transmitter install for a week and when i got back , i stopped by my friend's place ... he was in the middle of tearing down the engine .
my friend said that he called the old boy that had worked on john deere and other equipment since christ was a corporal and explained the situation . the guy said to pull the sleeves .

while i was putting on a pair of coveralls , his wife brought out a big tray of sandwiches , a pot of coffee and other sundry items .
i looked at my friend and said "looks like i'm in for the duration" .
we got the engine apart and got the sleeves out ... there were small areas of porosity about midway up from the bottom . the best description i can give is "sort of spongy/sintered looking" .
the old boy had said that these were flaws in the castings that did not show after the initial machining .
over time , after a little wear and compositional changes they showed up , it was a known defect with certain era/dates of production runs of the sleeves .

well.. maybe i'm over reacting this.
On tuesday i can pick one of my guys to help me examinate this issue a bit deeper.
JB weld .. well i have not ever glued an engine block with it, so i have no experinece on how durable will it be.
On the otherhand its a russian block.
my fork lifter had a similar problem, i got that for free.
it had a crack on the block too, it was fixed by a man who has just gotta be verr optimistic. they drilled 4 holes around the crack and simply bolted a small sheet of metal over the crack and sealed it with high temp. resistant silicone glue.
i have a replacement engine for that thing, for like.. 5 years now or so, when i got the little forklifter i purchased it. want to swap engines only if the original goes dead. Witch still has not happend. dunno how

I hope there is no crack on the inside and i only have to glue that small hole.

when i started this engine up, the one in question that is, sound was okay.
it did not sound like there is a problem.
the smoke was kindof grey, but keeping in mind it was not running for years, and its winter time it may not be related to water in the cylinder.
I hope even if there is a hole on the otherside of the block, it leads under the piston workrange, into the oil.
if I'm lucky maybe we can get away gluing it without taking the whole darn thing apart, by removing only the oil pan.


would it work, if after gluing the whole i know of, to let compressed air into the water system ? I could do that via the radiator, where the coolant can be refilled. I can probably use the air compressor to blow air in, it has a gauge to show tire pressure but i assume if i pressurise the system with say.. 2 bar, and it holds this pressure then i can safey assume there are no other cracks int he system, right?
if it leads to the oil pan then the bubling oil would make a noise, if nothing else the air comming out would.
darn, this is getting on my nerves, actualy i have an urge to go out and take it apart now, but if i do that.... its sunday, I'm sure my miss will not gona let me in the house for a while
just gotta stay on my arse now...
frustrating.
sure, if its dead then no problem i just use a tracktor. but it would be sooo pointless to have a tractor power a stationary equipment that can be run from a stable engine...

thank You for the help regardles. Will post back as soon as possible.

weld a tab of steel near the area and snap it off. if it takes a little cast with it its the correct rod etc.

Assuming they drilled all ends of the crack for stress relief first, this method would beat an epoxy patch or lousy weld job.

If the cylinder sleeves are wet, they're prone to osmosis, which eats tiny holes thru the sleeves over time while the engine is running. Reverse osmosis coolant filters greatly reduce this effect (if so equipped). My point is that a coolant leak into a wet cylinder isn't necessarily caused by freezing. However, any near-penetrating osmosis holes left when it was parked may have corroded through if it's been sitting for a while.

Dry sleeves don't have that problem, and might not even crack if the block nearby does.

osmosis ?
wasn't that the evil brother of osirus ?

Perhaps yer thinkin' of molasses...

well , it is getting close to january ....

this, i must say is intresting.
We are done with the crack issue, thank You all for the feedback
We used cold welding. Nothing special, no preheating or what so ever.
The whole original weld it self cracked, so we cleaned it a bit.
We found that there are actualy numerous small, verry small cracks where water escaped. Most of them where so small that after drilling it out with a verry small drill, starting an arc allmost was enough to get it done.
My "engineer" encourged that we should not bother to get the block out and heat it up and etc.. just leave it enough time to cool down after every single weld point.

meanwhile we undressed the engine a bit, and man, I personaly never seen this kind of intresting stuff. And it makes perfectly no sense at all.
There is a big front plate on the engine, removing it revealed, that the generator and the waterpump have shared shaft. Its a single shaft for the 2. And this shaft is actualy the shaft moving the valves. (? I mean come on, WTF?)
Sure it looks a decent build, but i never seen it like this.
I seen a similar setup where the water pump + compressor+ generator had the same shaft and all this was driven from the engine main shaft via a chain, but why on earth would drive the waterpump and the alternator from the shaft that moves the valves ??
Is this some rusky joke i don't get, or it has some -or any at all?- sense to do it this way?
allso an intresting feature is the oil pump, witch is not built into the engine, rather THAT IS driven with a belt from the engine main shaft.
--> this may actualy be a good idea. easy to change.. <--
Wierdo, if i knew before that its an intresting or.. at least rare engine (or just stupid as it is) i might had started working on it sooner.

The "engineer" told me that some engine designs of the straight 8 cyl ones are actualy 2 4 cyl engines made to act as one.
Short valve controll shafts are harder to twist, those engines usualy have the shaft driven from the middle of the engine. And prehaps this engine is a "byproduct" of that kind of setup. The shaft extension where the generator and the waterpump had be assembeled on might had the orignial purpose to allow some space for a mechanism to connect it to the next engine section. Witch still makes no sense for me at all.
Or rather, i would suspect the engine designer was given a set of parts to incorporate in this engine. Allso the sleevs are intresting, they are at minimum 5 cm wall thicknes. Maybe just a change of sleevs and pistons are the way to "upgrade" it to a higher capacity engine ? The stuff if pretty mutch roboust, absolutely overkill for the 50 hp power rating.
And allso its quite a tall engine, it has unusual stroke/bore ratio.
The metal plate says 50 hp at 1400 RPM, and idle at 600 RPM.
Maybe it was ment to be a marine diesel ?

it is not uncommon for stationary diesels to run at low rpm ... especially the "brute force" design types .

that "thing that moves the valves" is commonly referred to as a "cam shaft" .
man , the drive gears and/or chain must be substantial to be able to supply the additional torque .
the designers must have been confident in the design of the generator/alternator and water pump .
an outboard oil pump that is quickly changeable is a good idea ... you can run without an alternator and even gravity feed water for cooling but with a failed oil pump one is out of the running .

good clear pictures or a link to the engine would be helpful .

Űthe gears driving the "cam shaft" are about 2.5 cm wide.
straight toothing, looks nuke-proof.
not a verry precise work, the stuff has -khmmm- some dead zone.
got its own oil pan.
the generator is not a usual stock russian one, for sure.

But for what reason would one get into the trouble of designing a new generator that runs well on cam shaft speed, not to mention the waterpump?
Sofar I only seen those geared higher than engine main shaft RPM, and russians are great at re-cycling what they stockpiled up during the communist era.
making a new part with the exact same role as one that is allready on hand by the hunderd(or hundreds of thousand, who could tell for sure..) seems "un-russianistic".
I will try to get some pics before we assemble it again.

If it's just a tiny pinhole, epoxy it. You'll get a better job if the engine is drained & warmed to dry it. Sandblasting the area will also help.
If it still seeps a bit, just add some of that radiator leak stopper chemical & leave the cooling system unpressurized.
The material with sodium silicate & copper fibers works the best. This stuff will seep out with any leakage & dry in place to seal the leak. The copper fibers help fill cracks. However, it could take several run cycles before the leaking stops completely, as dry deposits of silicate may take several coats to build to enough strength.
As long as the cooling system isn't pressurized, this leak 'repair' can easily last the life of the engine. You just have to keep a close eye on water levels & make sure the level stays full.
The stuff isn't expensive & could hold you until you have to take the block apart fofr some other reason.