Has anyone done an in-frame 3116 rebuild?

[Reworked LMTV]

Just curious if anyone has done a CAT 3116 in-frame rebuild on a FMTV. I have minor blow-by, but may decided to do the pistons and rings and anything else out of spec. It runs great. Bet it idled too much during it's tour.

I have the Carpenter Kit to do the top end. So that should make the job a bit easier.
​https://youtu.be/sVnRSJDOO7s

 

[NDT]

I had major blowby until I changed the clean appearing engine oil. Blowby gone. Worth a shot.

 

[Reworked LMTV]

I had major blowby until I changed the clean appearing engine oil. Blowby gone. Worth a shot.

Maybe a stuck ring?

 

[NDT]

Maybe a stuck ring?

My guess was moisture in the crankcase from sitting. The blowby was possibly water vapor.

 

[Ronmar]

Yep more than one way to set the top end...

You might have to pull the rad and intercooler if you had to pull the cam, but you should be able to hone and re-ring provided you don't find anything out of spec.

 

[m-35tom]

blow by is always the top ring. you need to do a leak down test to see what you have wrong before taking it apart.

 

[Ronmar]

Yea, but a leak-down on a 3116 seems a little more difficult without some cat SST made out of unobtanium, to separate the injection port from the fuel gallery...

In the end, the blow-by indicates something is worn. Are you going to go to the trouble of stripping down the top end to replace a single ring? If this were an engine I had to have in operation again ASAP, maybe just to save time and get a system back online.

For a hobby vehicle, I think if I am going to the trouble of pulling the head, i will inspect and measure, I will hone and re-ring all 6, and re-seat all valves and replace valve seals while it is apart.

 

[m-35tom]

OK, well you have to be old to know this, but if this is a low hour engine and you are only concerned with re seating the rings, take the intake off, disable the fan, get a box of BonAmi and with the intake disconnected dust it into the engine at an idle. This WILL work for compression and oil consumption. This assumes there are no broken rings and no other reason to take the engine apart.

 

[simp5782]

First thing you need to do before taking anything apart is send your oil in for a sample and get a wear report from Blackstone Labs. This will let you obviously know if something isn't right. 2nd thing while waiting is to check the blow-by pressure. A certain amount is allowed and yours could be within specs you just do not know what the specs are. . This would be before you take anything apart. So get to that point before even considering an in frame.



I will add a question. Do you have any oil leaks? Front crank seal? That will be the first to go if you have excessive blow by. If you don't have any oil leaks then please check the pressure.

Oil consumption is 1 gallon of oil per 60 gallons of fuel consumed - THIS DOES NOT COUNT LEAKS. Anything more and you have an issue there.

to check blow by You need a water gauge and a hose. and hook the hose onto the oil dipstick. Run it at high idle. Low idle and medium idle. Should not see anything over 3.5psi Over 4 and seals and everything else start going

 

[m-35tom]

^^^ Exactly.

 

[Ronmar]

OK, well you have to be old to know this, but if this is a low hour engine and you are only concerned with re seating the rings, take the intake off, disable the fan, get a box of BonAmi and with the intake disconnected dust it into the engine at an idle. This WILL work for compression and oil consumption. This assumes there are no broken rings and no other reason to take the engine apart.

Yes, basically re-honing the rings, not that old of a trick, or I am not as young as I still think I am Probably why I keep injuring myself...

The issue here without records, or hour meters on these surplus vehicles, usage is an unknown...

lots of tools for evaluation, but that wasn't the OP’s question... He said minor blow-by, which means it is probably well within spec, but perhaps annoying to him?

 

[scottmandu]

Another reason to buy a truck with a C7 or 3126, you know how many miles and hours the engine has run.

 

[Ronmar]

Maybe, can you get one of those for $3500?

lots of cool info in the ECU engines, Unless the ECU has crapped or been swapped in the past How many ECU’s,have we heard about dropping their memory because their internal battery has failed... I am sure a few have failed before they were surveyed.

This is kind of like the speedos being swapped during depot overhaul... Without the maintenance history, op hours and actual mileage are a crapshoot...

 

[Reworked LMTV]

Good ideas all. I actually have manometer from another project that I can use. As far as leaks go, I have not seen any. Yes, Blackstone. I used them from my car. Great info. I did get a oil test from GOVPLANET, but hard to say it was accurate since the oil looked fairly new. No excess anything in that test.

 

[Reworked LMTV]

Another reason to buy a truck with a C7 or 3126, you know how many miles and hours the engine has run.

Well yes, but that mileage and hours vs actual wear are not always correlated. However, testosterone levels of the drivers and wear is highly correlated lol

 

[Reworked LMTV]

http://www.astleford.com/pdf/dt466dt530brochure.pdf
I will pursue the pursue the previously mentioned tests/ideas.

I'm always looking at alternative engines. Not sure I would pursue them but always thinking. Interesting, the International DT series would be a nice replacement engine, if it is needed. The 570 is not shown, but it is even more powerful. Dimensions would likely work. Sleeves for in-frame rebuild. Lots of them out there. Diesel mechanics like them. Avoid first year of production.

Let the flame comments begin lol

PS have you guys seen the new CAT 7.1? 425 hp and is pegged as a 3116, 3126, and C7 replacement.