Working on diagram of Cat 3116 common failure points

[Reworked LMTV]

Working on diagram of Cat 3116 common failure points

Please provide input on any other areas that you have found, so that I can add.

Open to input from all on this project

Will do the 3126 and C7 too, if people provide info. specific to these engines.

I may do the drive train later.

Diamonds now colored for relative importance of addressing.


3116 photo in pdf for educational purposes only.
The picture is not mine. Because it shows the engine devoid of plumbing, it makes it easier to visualize.

[HR][/HR]

 

[snowtrac nome]

I spent quiet a bit of time diagnosing air in my system first thing I replaced was the failure prone fuel filter than I did the hoses between the lift pump and the tank. the problem still persisted. A little back ground is this problem came on over last winter I thought it was just because it was cold but as summer came around I knew I had a problem as time went by and I failed to fix it the problem got worse. finally I replaced the return line to the tank and the problem was fixed, I don't pretend to know how this worked other than the return line must go to the bottom of the tank like the stand pipe. I found it on a school bus forum where a guy kept telling every one if it only leaks down over night replace the return hose he was right as a note to others if your system sucks air every time you shut it off look at suction side if your truck only sucks air overnight look at the return hose.

 

[coachgeo]

... I don't pretend to know how this worked ....

hmmm..... could it be that the return is a bit blocked and once engine off.... pressure on the return system being so stuffed full; overnight the pressure seeks easiest path to release... which is to push the fuel back thru the whole system in reverse sucking air in thru the tank return as it does so?

 

[Ronmar]

Lot of check valves to suck back thru... I don’t see a return line causing an issue by itself without bad check valves in lift pump and primer pump/primary filter, unless it is pouring fuel on the ground when the engine is running it doesn't appear to return to a standpipe, only a port on the top of the tank...

 

[Reworked LMTV]

Thank you. I will add a note about this.

I spent quiet a bit of time diagnosing air in my system first thing I replaced was the failure prone fuel filter than I did the hoses between the lift pump and the tank. the problem still persisted. A little back ground is this problem came on over last winter I thought it was just because it was cold but as summer came around I knew I had a problem as time went by and I failed to fix it the problem got worse. finally I replaced the return line to the tank and the problem was fixed, I don't pretend to know how this worked other than the return line must go to the bottom of the tank like the stand pipe. I found it on a school bus forum where a guy kept telling every one if it only leaks down over night replace the return hose he was right as a note to others if your system sucks air every time you shut it off look at suction side if your truck only sucks air overnight look at the return hose.

 

[Reworked LMTV]

I think I recall that the fuel filter primer pump is a problem area too. Is that correct?

I spent quiet a bit of time diagnosing air in my system first thing I replaced was the failure prone fuel filter than I did the hoses between the lift pump and the tank. the problem still persisted. A little back ground is this problem came on over last winter I thought it was just because it was cold but as summer came around I knew I had a problem as time went by and I failed to fix it the problem got worse. finally I replaced the return line to the tank and the problem was fixed, I don't pretend to know how this worked other than the return line must go to the bottom of the tank like the stand pipe. I found it on a school bus forum where a guy kept telling every one if it only leaks down over night replace the return hose he was right as a note to others if your system sucks air every time you shut it off look at suction side if your truck only sucks air overnight look at the return hose.

 

[coachgeo]

I think I recall that the fuel filter primer pump is a problem area too. Is that correct?

Yes

 

[Reworked LMTV]

Added. Thank you!

Yes

 

[Reworked LMTV]

Do I recall someone says their torque converter nuts were loose?

 

[simp5782]

Do I recall someone says their torque converter nuts were loose?

cause the morons didn't use locktite and properly torque them down.

Not a common problem to the engine itself.

Just post the video that Adept Ape has posted. He is the CAT guru. He gives a decent video all around on the engine for those folks that are novice or completely clueless about CAT engines.

 

[Ronmar]

Except I think most of the problems the LMTV have are unique to the engine config used in the LMTV...

Yes, check the flywheel to tc flexplate bolts.

The primary filter issues are probably not for failures, but for maintenance issues. Crud in the flapper check under the filter housing(fuel bypasses thru here when running) will disable the primer function. Holes in suction line will inhibit fuel lift from the tank. I am sure there have been instances of the bulb cracking, but I think those are probably not very often and the assembly probably gets changed for something less sinister.

https://youtu.be/ZthRpf79gTg

https://youtu.be/W7If-mz3vFo

 

[Reworked LMTV]

Thank you. Exactly what I was thinking.

Except I think most of the problems the LMTV have are unique to the engine config used in the LMTV...

Yes, check the flywheel to tc flexplate bolts.

The primary filter issues are probably not for failures, but for maintenance issues. Crud in the flapper check under the filter housing(fuel bypasses thru here when running) will disable the primer function. Holes in suction line will inhibit fuel lift from the tank. I am sure there have been instances of the bulb cracking, but I think those are probably not very often and the assembly probably gets changed for something less sinister.

https://youtu.be/ZthRpf79gTg

https://youtu.be/W7If-mz3vFo

 

[Reworked LMTV]

Adept Ape has shared a lot of good info. So does the guy at Mechanics Hub.

What I am trying to do is a quick check list of things to check before you go on a trip or something. There is a lot of good info. on this site, BUT it is not conveniently organized. If I am going to a trip, I want a list to be able to quickly reference, not hunt all over this site and spend hours.

 

[tennmogger]

Check the oil pressure sender. One loosened and backed out, costing me an engine.

What we need is an absolute alarm if oil pressure drops.

 

[Reworked LMTV]

I'd like two sensors. One there and one after the governor.

Check the oil pressure sender. One loosened and backed out, costing me an engine.

What we need is an absolute alarm if oil pressure drops.

 

[Ronmar]

And back to the LMTV specific issues. Cat made a lot of these engines, with that same oil line, compressor and oil sensors. Don't hear about oil line failures And parts falling apart so much from the commercial users who put lots of miles on these engines. I am sure if they were prevalent we would have heard something... parts breaking and falling off indicate vibration issues. Driveshaft runout, spline hinge/play, ujoint play and of course overall balance. Hub bearing play and wheel balance could also be a factor. And of course run a wrench over things regularly...

an oil level sensor in the sump might be a good idea. A shroud over the oil lines and sensors with a sump and an oil sensor to quickly detect an oil leak might also be an idea.

 

[Awesomeness]

Working on diagram of Cat 3116 common failure points

Please provide input on any other areas that you have found, so that I can add.

Open to input from all on this project

Will do the 3126 and C7 too, if people provide info. specific to these engines.

I may do the drive train later.

3116 photo in pdf for educational purposes only

[HR][/HR]

I think a lot of the diamonds are in the wrong places, or at least would be confusing to people new to the FMTV. For example...
- Diamond 1 (compressor gear nut loose) should be where diamond 3 is, directly on the front of the compressor.
- Diamond 2 (governor oil line) should be lower, between diamonds 3 and 9, because it's the compressor oil line that has cracked for some people, not usually the governor one.
- Diamond 3 (compressor bolts) should be where diamond 9 is, because it's the rear bracket bolts that come come loose, leaving the heavy compressor to vibrate freely cracking the front housing and/or oil line.
- Diamond 6 (old fan) should be left of diamond 3, where the fan is.
- Diamond 8: Are you talking about the flywheel bolts? The torque converter isn't really accessible from the engine.

Overall, I question whether most of these are really "common" issues. If the bar for becoming "common" is that "a couple people posted about it", you're going to have to put diamonds all over this picture! I view the problem differently - what is the likelihood of the problem happening versus how catastrophic will it be if it occurs? Losing the compressor oil line because the bolts are loose is mildly unlikely (military mechanics seem to put these back together poorly), but quickly ruins the engine so is quite severe, and is also easy to check/prevent. In this sense, it's important to cover issues that are quickly catastrophic, before getting too concerned about problems that cause issues slowly, or will not destroy the engine/transmission/etc. For example, I think there are a lot of people still running the old fan setups - while it's worth checking (and that would require more instructions than a diamond on a picture, obviously), it probably isn't reasonable for people to need to replace it immediately only because some people have wrecked a radiator over it. So a better bullet for that would be something like "ensure rubber fan vibration damper ring is not damaged, and fan components fit tightly and without slop/wiggling".

These kinds of guides can be very helpful. Be sure to look through the guide here in my signature, too.

 

[Reworked LMTV]

I think this is a work in process, conceptually and otherwise. My goal is to reduce failures in general, especially CAT O' Strophic ones . This was just to get the ball rolling.The diamonds don't really have to be exactly on the right spot for now, just the general area. It looks easy to put diamonds on exactly the right spot, but I am finding that it is not. Better / larger pictures will help. Right now I am looking for input from anyone who has had 3116 failures and any pictures of damage. Statistical tabulations would be helpful, but impractical, and sample size would be questionable. Maybe a simple survey should be done. Specifics I am happy to add. For example"check the rear bracket bolts" as you mentioned.

Yes, I think that all areas are potential areas for failure, but obviously some occur more often than others. Particularly if the surgeons were sloppy. Maybe a red diamond for highly likely, yellow somewhat likely, blue for reported area of failure. Maybe use red $$ catastrophic, A tow truck symbol for "could leave you stranded". Lots of diamonds is a clutter problem, but at least attention is drawn to it. I will make the diamonds smaller, or whatever is less intrusive.

I think a lot of the diamonds are in the wrong places, or at least would be confusing to people new to the FMTV. For example...
- Diamond 1 (compressor gear nut loose) should be where diamond 3 is, directly on the front of the compressor.
- Diamond 2 (governor oil line) should be lower, between diamonds 3 and 9, because it's the compressor oil line that has cracked for some people, not usually the governor one.
- Diamond 3 (compressor bolts) should be where diamond 9 is, because it's the rear bracket bolts that come come loose, leaving the heavy compressor to vibrate freely cracking the front housing and/or oil line.
- Diamond 6 (old fan) should be left of diamond 3, where the fan is.
- Diamond 8: Are you talking about the flywheel bolts? The torque converter isn't really accessible from the engine.

Overall, I question whether most of these are really "common" issues. If the bar for becoming "common" is that "a couple people posted about it", you're going to have to put diamonds all over this picture! I view the problem differently - what is the likelihood of the problem happening versus how catastrophic will it be if it occurs? Losing the compressor oil line because the bolts are loose is mildly unlikely (military mechanics seem to put these back together poorly), but quickly ruins the engine so is quite severe, and is also easy to check/prevent. In this sense, it's important to cover issues that are quickly catastrophic, before getting too concerned about problems that cause issues slowly, or will not destroy the engine/transmission/etc. For example, I think there are a lot of people still running the old fan setups - while it's worth checking (and that would require more instructions than a diamond on a picture, obviously), it probably isn't reasonable for people to need to replace it immediately only because some people have wrecked a radiator over it. So a better bullet for that would be something like "ensure rubber fan vibration damper ring is not damaged, and fan components fit tightly and without slop/wiggling".

These kinds of guides can be very helpful. Be sure to look through the guide here in my signature, too.

 

[AllenF]

I think this approach is great. As has been mentioned, there is a great deal of excellent information here. But it is all over the place and requires a long and involved search to find it. I was thinking more along the lines of something like Fuel System, Coolant System, CTIS System, Electrical System etc. After each system is listed then have a brake down list of each component for this system and then all of the info there to resolve every known issue including TSM's and after market part numbers and places to get them from. This could be done for the 3116, 3126 and C7. Each needs it own place to better focus on only one and not all 3. Yes this will present some common things being posted three times but it will be complete for each type. There could also be sections for issues unique to the different versions such as M 1078, 1083, ect. Also A0,A1 ect. A unified format would also be needed to eliminate confusion and simplify searching.
I know a ton of work but in the end it could make every ones life a lot better. Most likely this would become a new section with factual info only unlike the forum threads with a lot of unnecessary applause and chit chat. Which I love but is in the way of having a faster way to get what is needed to solve our issues. My

 

[Reworked LMTV]

I see that you recently joined. Welcome!

Wow, ok, but this would be a massive project. I think that we could add more things with time, but lets start smaller first. I see this as a quick reference, but eventually links could be added to TMs. This is essentially a prototype tool with significant future changes. Those who provide input will be mentioned in the credits. Just give me time to put all this together : )

I think this approach is great. As has been mentioned, there is a great deal of excellent information here. But it is all over the place and requires a long and involved search to find it. I was thinking more along the lines of something like Fuel System, Coolant System, CTIS System, Electrical System etc. After each system is listed then have a brake down list of each component for this system and then all of the info there to resolve every known issue including TSM's and after market part numbers and places to get them from. This could be done for the 3116, 3126 and C7. Each needs it own place to better focus on only one and not all 3. Yes this will present some common things being posted three times but it will be complete for each type. There could also be sections for issues unique to the different versions such as M 1078, 1083, ect. Also A0,A1 ect. A unified format would also be needed to eliminate confusion and simplify searching.
I know a ton of work but in the end it could make every ones life a lot better. Most likely this would become a new section with factual info only unlike the forum threads with a lot of unnecessary applause and chit chat. Which I love but is in the way of having a faster way to get what is needed to solve our issues. My