[Brighty]

Ok, so have head off and tidying up the block ready for new head and gasket to go on...... found what I think is a hairline crack at the back of the block behind cylinder 4.
Can anyone confirm if this looks to be what I think it is? Block is flat and true to less than 0.0015 using engineers straight edge and feelers, both end to end and side to side, as well as any other angle I tried across the whole surface.
Next question.... can I run it??(what outcomes? how long will it last??) OR can it be fixed(how/whats involved?) OR am I looking for a new block which are rare as %*&^ over here in Australia??

 

[RichandLuke]

Can you magnaflux it? May be others you can't see.

 

[char1355]

We don't see a crack in blocks all that often but the #4 cylinder would be one area where it can happen. That cylinder gets the hottest. Sometimes we see a failed piston cooling nozzles there which often results in a rod sticking out the side of the block. That crack appears quite long and not sure how deep it goes.

 

[Brighty]

We don't see a crack in blocks all that often but the #4 cylinder would be one area where it can happen. That cylinder gets the hottest. Sometimes we see a failed piston cooling nozzles there which often results in a rod sticking out the side of the block. That crack appears quite long and not sure how deep it goes.

Thanks Char. Not exactly the news I wanted or needed to hear. Can it be repaired? What’s the likely outcome if I run it?
Or am I simply looking for a new block that will be almost impossible to find here in Australia?

 

[edpruss]

That crack appears it might be following the OD of the cylinder where it intersects the underside of the head surface, if that is the one you are talking about, if so, perhaps a core shift has the head mat’l too thin, leading to the crack. No cure. I am sure others might have other points of view?

Ed in CO!

 

[Redark1]

before you pulled it apart did you have any cooling issues or any pressure in the coolant system like loosing coolant. you might try some kind of dye and let it sit for a bit, then sand the surface and use some acetone to see if it draws anything out of the metal after sanding.

 

[Brighty]

before you pulled it apart did you have any cooling issues or any pressure in the coolant system like loosing coolant. you might try some kind of dye and let it sit for a bit, then sand the surface and use some acetone to see if it draws anything out of the metal after sanding.

Yes mate, the initial problem that started everything was coolant system pressurising and pushing coolant out the overflow. Being an '1987' vintage engine and doubt it had been opened when I bought the car, went firstly to head and/or gasket. Ordered new head through DCEC and reinstalled with OEM Cummins gasket and ARP studs. Failed to do a hot retorque once running as we were in a rush to get it going to move house at the time. About less than 2000km after getting it running the top radiator hose was getting 'hard' again but not pushing coolant and had quite a few oil leaks as well sooo..... thats where I cracked the shits and pulled the engine to fix everything correctly, oil leaks and pull the head again to get O'ringed. Side note to the story was that I did manage to get it 'tuned' by a local mob that was recommended but now find out after removing the head, the pump(VE) timing was advanced way too far which explains why it was so bloody smokey and egt's climbed so quickly. I was always pretty careful with it and never let it go over 500c much unless I was climbing hills on the highway but was backing off to keep it as low as possible.

Any recommendations on where to buy a new block and can ship to Australia?

 

[Brighty]

Ok guys, I got hold of my contact at DCEC in China for a quote on a bare block in the hope I can possibly get one in, replace main bearings and seals etc and build up from there. My current issues aside with the likely cracked block, it has had pretty much everything replaced.... new water pump, oil pump, thermostat, colt cam, DCEC head with 60lb springs, good VE pump, rebuilt injectors, brand new HX30 Super and have port matched exhaust manifold. Hoping I can change everything over without too much drama. Need new pistons?? (for better performance??) Happy to go for power if Im going to build it up so any more upgrades..??
Got quoted $835 USD for the block + $840 USD freight to Australia (Part# 4991816)
Current engine has ESN 44127375 1987 vintage I believe.

Will this block part number work for the engine I have to swap everything over??
Anything else to take into account or be concerned about??

 

[char1355]

Your engine is a bit older than you think. It is a very early one produced March 14 1985 at the Consolidated Diesel plant in Rocky Mt. NC here in the USA. It is a commercial model BT3.9-C100. Now, as for the engine block, this is going to be a guessing game because Cummins no longer shows a replacement block for that engine. If you look at the turbo side of the block, do you see 2 large freeze plugs to the left of the oil filter? That is normal for the early style blocks. That changed in the1990's to a new block called STORM. On those blocks you will find 1 large freeze plug and 1 smaller screw in type plug where the block heater would be fitted. I looked up an engine built in 1987 which should have the same block as yours and it shows the following part numbers. Starting with the newest which is the one that is current they are 5449532, 3934565, 3929045, 3928794, and 3916251. The part numbers for the STORM blocks are 3933224, 5405080, 3938366, and 3932012. This notes this is for all 4bt engines 1991 and newer. The block number 4991816 you list shows to be a non sellable item in the Cummins system. Now what does all this mean. Well, first, if you planned on a block heater and used the newer style block you'd need an updated version. Second, STORM blocks handle the oil filtering differently so you would need a different oil filter housing, oil filter gasket, and possibly a new oil pump. STORM blocks circulate oil at a higher rate than most older styles. All this being said, this is an I don't know for sure situation. You need to contact Cummins. Give them your engine serial number (ESN) and tell them the situation. They will tell you the correct replacement block. You can ask them about the block part number you found. That may be a foundry casting number and not a part number. Also ask them about the oil filter mount, gasket, and oil pump as to whether they have to be changed. If you can't work it out I'll go through my Quick Serve and ask the questions. I don't mind doing that.

 

[Brighty]

Your engine is a bit older than you think. It is a very early one produced March 14 1985 at the Consolidated Diesel plant in Rocky Mt. NC here in the USA. It is a commercial model BT3.9-C100. Now, as for the engine block, this is going to be a guessing game because Cummins no longer shows a replacement block for that engine. If you look at the turbo side of the block, do you see 2 large freeze plugs to the left of the oil filter? That is normal for the early style blocks. That changed in the1990's to a new block called STORM. On those blocks you will find 1 large freeze plug and 1 smaller screw in type plug where the block heater would be fitted. I looked up an engine built in 1987 which should have the same block as yours and it shows the following part numbers. Starting with the newest which is the one that is current they are 5449532, 3934565, 3929045, 3928794, and 3916251. The part numbers for the STORM blocks are 3933224, 5405080, 3938366, and 3932012. This notes this is for all 4bt engines 1991 and newer. The block number 4991816 you list shows to be a non sellable item in the Cummins system. Now what does all this mean. Well, first, if you planned on a block heater and used the newer style block you'd need an updated version. Second, STORM blocks handle the oil filtering differently so you would need a different oil filter housing, oil filter gasket, and possibly a new oil pump. STORM blocks circulate oil at a higher rate than most older styles. All this being said, this is an I don't know for sure situation. You need to contact Cummins. Give them your engine serial number (ESN) and tell them the situation. They will tell you the correct replacement block. You can ask them about the block part number you found. That may be a foundry casting number and not a part number. Also ask them about the oil filter mount, gasket, and oil pump as to whether they have to be changed. If you can't work it out I'll go through my Quick Serve and ask the questions. I don't mind doing that.

Thanks for the very detailed reply mate.
To answer a few things.... yes, my engine has the two large freeze plugs on turbo side next to oil filter.
I have no need for block heater here in Oz so no issues with that on a new block.
New oil pump I put on my engine was from a 6bt so assume as it fitted my older block no issues, should swap over ok.
If I needed to get a new filter housing, so be it.
My main concern is, would the main components from my very old engine.... ie crank, pistons, rods, cam etc all swap over to a 'storm' block?