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Working On The M561 Gama Goat

mkcoen

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I am new to this engine so I can't be of much help with this problem. I did purchase a injector timing gage from a outfit who claims to be the authority on these engines. Give Stephen a call @ 504.362.2371 and see what he says, probably a good source for the thermostat as well.
I'll need to call him next week. While the thermostat NAPA came up with is the same diameter it's too short. The bottom end of the one on the Goat seals another passage and the NAPA one isn't set up for that. Once I get a verifiable part and number I'll post it.
 

mkcoen

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Spoke with Stephen this morning. He said the NAPA thermostat would probably work okay as the military used different specs for temperature control on the engines. He's still going to try and look up what the correct one would be based on the engine serial number. He seemed to think the number I gave him was short but scrubbed the block down and this was the whole number on mine - 3D-68099 and the last nine wasn't stamped that deeply into the pad but there certainly wasn't anything after that. Anyone else have an example of their block serial number to compare it with?
 

mkcoen

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My boss on the engine had a two line number, first line is 5033-6299, second line reads 3D-68963.
He said the 1st line was just the series number and the "3D" was the serial number. Looks like both of ours have the same number of digits so that should be right. I haven't heard back from him so guess I'll need to follow up tomorrow.
 

mkcoen

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Also found this, part number is the same the TM calls for, a bit pricey though.

http://store.reliableindustries.com/engine-parts/3038144-thermostat-assy-3-53-170-deg-opening-temp/
That is the correct one. When talking with Stephen he said the extra bit that blocks the water passage could be because the military specs wanted a variation in the temp ranges. He seemed to think the NAPA thermostat would work fine under normal circumstances. I'll probably go ahead and put that one in while trying to get the correct one for a spare. Here's some side by side photos. The original is on the right. NAPA $6 vs $62 + $19 tax and shipping on the other one. I'll keep looking for an alternative to the original that might be a little cheaper.
 

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mkcoen

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Okay put the NAPA thermostat in. Drove the same route I did the other day and it's 90° out so similar conditions. Temp gauge got up to 180° and held steady. I parked the Goat in the driveway and left it idling for 30 minutes. It was still at 180° so pulled into the shop and shut it down. Still have the leak from the air box tube. If it wasn't headed for 103° today I'd take it for a longer drive but think I'll wait for some cooler temps.
 

mkcoen

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Sounds like positive results.
That air box tube is driving me nuts though. It's actually pulsing now that it's in the shop. It'll go about 5 seconds with a couple of drips then *BOOM* a short stream of straight coolant. Something is screwed up but I can't figure out what it is or how serious it is.
 

mkcoen

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I posted there and over at DieselStop.com. Maybe between the 2 sites someone will have an idea. By reading some of the sites I'm wondering if the liner seals weren't damaged and it's letting the coolant through somewhere it shouldn't be able to get through. After changing the radiator I really don't like the idea of having to do something more serious.

Let this be a lesson to all of you Goat owners: new belts and a new thermostat NOW! And pay attention to your gauges (that goes for everyone)! Don't wait until something like this happens even if it seems to be running fine.
 

mkcoen

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Thanks to m38inmaine looks like we have an answer to the Goat issue. He found a thread with a description of exactly what it's currently doing and how it would have gotten to that point.

~"Had a tired old 3-53 in my backhoe (rest in peace). I second the notion that these motors just keep running, long after they have excessive wear. FYI, these motors do not have a "head gasket" in the sense you'd be used to on a regular engine. There are lots of orings under the head sitting on top of the block that can be damaged if the engine is overheated. Also, this motor has pressed in sleeves of the "wet" variety. The coolant surrounds part of the sleeve, and there are large orings to keep the coolant from getting into the crankcase, or air box. These also get trashed in an over heat. Good news is, an inflame rebuild kit is darn cheap compared to many other diesels. It'll come with liners, pistons, and all those afore mentioned o rings. There is a small pipe on the side of the crankcase, that points towards the ground. See if any coolant is coming out of it. That's the air box drain, to let condensation drain, but if it has coolant coming out you probably have toasted orings."

So while it is a serious issue it's not insurmountable. After changing the radiator I don't really relish the idea of pulling the head but it beats pulling the engine.
 

Petesos

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Hi All
Been reading this thread for most of this morning and when you consider what you have done with this Vehicle from start to near finish , (and what a job you have done )
removing the head would be a walk in the park ....It is so good to see restorations laid out in front of you in Pictures and verse .
Petesos
 

mkcoen

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Hi All
Been reading this thread for most of this morning and when you consider what you have done with this Vehicle from start to near finish , (and what a job you have done )
removing the head would be a walk in the park ....It is so good to see restorations laid out in front of you in Pictures and verse .
Petesos
Unfortunately I think it's going to go a bit beyond the head. If the liners have 0-rings also then there is the issue of pulling them as well. I'm not sure if that can be accomplished without pulling the engine. This is a bit beyond my basic mechanic abilities so I'm going to have to defer to someone with more knowledge. If it is just the head than I can probably handle it. Putting my hands into the guts of the motor and having everything work when I pull them back out might be more luck than skill.
 

Petesos

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Hi Again
I think you are underestimating the help that is available to you on this site Bud and that you are capable of , Each and any one of us could perform brain surgery if we needed to by just listening to folk who have walked the path already :mrgreen:
Pete
 

Tinwoodsman

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Not sure about the brain surgery part but I am really glad you found the proper diagnoses for a problem that I know has been really bothering you. Now...:grd:
 

combat32

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Mark thought I would just throw out this suggestion, talked to a friend of mine about you problem. He was a CW3 maintenance officer and used to work at the big Mainz rebuild shop back in the day. He opined that it would not hurt to re-torque the head bolts, it might be enough to make the o ring seal up, if it works great, if not you have lost nothing.
 

mkcoen

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Not sure about the brain surgery part but I am really glad you found the proper diagnoses for a problem that I know has been really bothering you. Now...:grd:
It is a relief to know what the problem is. Unfortunately I'm leaving tomorrow for 10 days so won't even have a chance to think about getting started on it until I get back. I have PM'd another member that is an engine builder to see if he'd be interested in doing it but still couldn't move it to his shop until after the 24th. I really want to do the Ft Hood Rally in October but I think that's going to be cutting it close. I better have it ready to go by Veteran's Day though as I plan on driving it to Austin (about an hour and half drive) while the Mrs. uses the trailer to haul her M37 for the parade.
 

mkcoen

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Mark thought I would just throw out this suggestion, talked to a friend of mine about you problem. He was a CW3 maintenance officer and used to work at the big Mainz rebuild shop back in the day. He opined that it would not hurt to re-torque the head bolts, it might be enough to make the o ring seal up, if it works great, if not you have lost nothing.
I'll give it a shot but as hot as the engine was (melted the solder on the radiator) I'm guessing the O-rings are probably toasted o's.
 

combat32

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You may be right, but it don't cost nothin. You may be surprised, but I bet those bolts will be loose.Might want to bring it up to operating temp first. Good Luck!
 

Gamagoat1

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P1010012 copy.jpgP1010010.jpg
That air box tube is driving me nuts though. It's actually pulsing now that it's in the shop. It'll go about 5 seconds with a couple of drips then *BOOM* a short stream of straight coolant. Something is screwed up but I can't figure out what it is or how serious it is.
If it's coming out of the airbox drain it means it has bad liner 0 rings. That's the only way water/coolant can be there, unless there is a crack. Up on the deck there are o rings and fire rings. The aluminum block requires silicone inserts and tubes for the water passages. This is not shown or mentioned in any of the TM's. I went thru **** getting a set from Detroit. They do not supply parts for the engine anymore. The Aluminum 353 was built for one vehicle, the Goat. Those that think or claim they have or will put a cast iron in a Goat are in for a surprise. They are not the same size.
 
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