2016 bobcat t770 d34p engine issue

[robdean]

So this is what i am looking at on my bobcat t770 with a doosan d34p engine.

It starts up easy and when on idle has no smoke and runs good. Once i try to idle up at all it wont idle and starts to dump black smoke like crazy.

I have a large amount of pressure buildup in the crankcase after it has run for a while. I was surprised when i took the crank case cap off it had a lot of pressure. I was shocked it did not push the dip stick out on its own.

I am looking to make or get an injector port compression adaptor to check compression thanks to Cowboy for the help on trying to find one.

I know blow buy and rebuild is the first place i go when i see that. But while i wait on the compression adapter what else should i check or is that the place everyone goes? Can anything else cause pressure buildup in the crankcase?

Thanks in advance.

 

[robdean]

If it helps to diagnose the engine issues i am looking at buying the software to talk to it.

 

[robdean]

So not that anyone cares but to followup with an update. The turbo is bad and the compression check on each cylinder is good. I ended up making a compression test adapter to run the test.

So thinking out loud i think my crank case pressure could be coming from a blocked SCR or DOC and could have caused the turbo to fail. Any thoughts on this?

 

[brdgbldr]

I wish I could help but I am not a diesel mechanic.

Hopefully someone can give you some feedback.

Please do keep us posted. I actually do read all post but only reply to ones that I think I can be of help to.

 

[fortworth-cowboy]

So not that anyone cares but to followup with an update. The turbo is bad and the compression check on each cylinder is good. I ended up making a compression test adapter to run the test.

So thinking out loud i think my crank case pressure could be coming from a blocked SCR or DOC and could have caused the turbo to fail. Any thoughts on this?

Take your DOC and SCR off and push some Air through. Also shake both and see if you hear rattling. If you hear some, they are bad.
Look also at your Dosing Module and see if there is a lot of DEF Fluid buildup.

 

[robdean]

So update.

I have never seen it before in my limited experience but with good compression (highest was 325psi lowest was 319psi) i still have way to much blow by and cant tell you why other then i have a bad cylinder or a few Its a lot of blow-by. So out the engine comes to see whats going on inside. I hate to rebuild an engine that has SCR and DOC and DEF on it. It seems like a waste but its the only one i have.

My question to anyone that reads this. Where do you all buy good rebuild kits and what brand? I cant find any on bobcat not even a part number so thought i would ask. I was hoping like with CATS they had different levels of kits but no luck finding one. I see a bunch from off brands are they any good?

 

[cmcneely]

So update.

I have never seen it before in my limited experience but with good compression (highest was 325psi lowest was 319psi) i still have way to much blow by and cant tell you why other then i have a bad cylinder or a few Its a lot of blow-by. So out the engine comes to see whats going on inside. I hate to rebuild an engine that has SCR and DOC and DEF on it. It seems like a waste but its the only one i have.

My question to anyone that reads this. Where do you all buy good rebuild kits and what brand? I cant find any on bobcat not even a part number so thought i would ask. I was hoping like with CATS they had different levels of kits but no luck finding one. I see a bunch from off brands are they any good?

 

[cmcneely]

I used Brian Sheely at Sheely supply outside of HOU. I couldn’t be happier. Brian provides a ton of information and feedback. My block had a spun main bearing and he has a process to address this. He carries OEM parts or can order.

 

[robdean]

Update

Engine is out and head is off. My first surprise was this engine is not sleeved. This changes the game a bit. Now it will not be as easy to rebuild if i need cylinder work.

So no smoking gun yet that would tell me why i had so much blow by and still meet compression specs.

Still have hash marks on cylinder walls. Except for a small area on each that matches the thrust angle. Its warn down a little but does not have any damage.

The rings look like they are possibly full of carbon as the pistons rock more then i would expect.

I will take the lower end down and pull the pistons next to see what story it tells.