XM818 of Death has died

[Ferroequinologist]

Not for good I hope.

Yesterday, my driver was returning from Charleston, SC to Winnsboro, SC (approx 120miles) with the empty M967 tanker. At mile post 176, he noticed the oil pressure had dropped a little from its normal running warm place (around 60psi) and the temp had gone up. He also noticed an occasional wiff of antifreeze. He didn't stop, he didn't call. He drove until the oil pressure dropped to about 15psi, and there was boiling antifreeze coming in the cab through the shifter hole. Then he stopped around 2pm, and called me. He was at MM 139. So he drove it, overheating, for 40 miles. He swears the temp gauge didn't go over 200, and if he had thought it was really serious he would have stopped.

Well, I get down there, and you can't even lay your hand on the engine. Took him home, and came back with Angie around 9pm. The engine was still warm. I brought another thermostat (figured that was an easy maybe fix) Replaced it, filled it back up, and she fired up. Had to go another 40 miles to the house.

Oil pressure was right up around 80psi when I started- by the time I got to he house, it had dropped to 25psi. Not really bad, but lower than it should have been. Now I didn't really notice anything either- until the oil pressure dropped, everything seemed fine to me, and I know what to look/listen/smell for. the temp gauge would go up to 190 or so and the new thermo would open and it would drop back down. never went over that.

About 5 miles from the house, the tem gauge started acting funny- also with the oil pressure dropping, I knew it was overheating again. I limped it to the house, and when I stopped there was steam pouring out of the overflow tube on the expansion tank and after I shut it off you could hear the coolant boiling in the block. NOT GOOD

Felt the radiator, and the top is scalding hot- midway down and the bottem is very very cold. So either I have a plugged radiator, another bad thermo, (both unlikely) or a failed water pump (that's my answer and I'm sticking to it.)

I just hope the other guy and I didn't do any major damage to the engine. I've put almost 12k miles on this truck in the year and 5 months I've owned it- she just needs a break probably!

 

[Marlboro]

Poor truck... I hope everything works out in your favor! Also glad you use it and work er like an ole mule

 

[USAFSS-ColdWarrior]

My condolence to the family and friends he leaves behind.

We trust that there will be a MIRACLE waterpump HEART TRANSPLANT and complete TRANSFUSION of VITAL coolant FLUIDS.

Practice your breathing exercises - that Mouth-to-Air-Filter-Canister Resusitation has deflated many a G.I.

 

[nk14zp]

Might be a pitted liner.

 

[Ferroequinologist]

I know, keeping my fingers crossed it is a 'simple' fix. I suppose I could have a blown head gasket too.

 

[bubba_got_you]

[FONT=&quot]If the pump were bad why would it get up to 190 then open and cool if the water is not flowing? I know it would be under presser in the block and force some cool water in but it would have to force a lot of water in to be noticeable. Because I live in Florida any trucks I keep I take the thermostat out because when it is 90+* outside the motor worms up fine without it. [/FONT]

 

[Ferroequinologist]

I know Bubba, it doesn't make much sense. But the temp gauge doesn't seem to be working right at all, so I'm not trusting it and will be changing the sensor and possibly the gauge.

The TM says that's the first thing to check, water pump flow. Next is to do a pressure test of the cooling system. From there though, it goes into evidence of coolant in the oil. But there isn't any in the oil. So I'm leaning towards a pump or clogged radiator.

 

[Westech]

I would have kicked that drives rear.. STATEMENT OF CHARGES ring a bell?

 

[bubba_got_you]

I know Bubba, it doesn't make much sense. But the temp gauge doesn't seem to be working right at all, so I'm not trusting it and will be changing the sensor and possibly the gauge.

The TM says that's the first thing to check, water pump flow. Next is to do a pressure test of the cooling system. From there though, it goes into evidence of coolant in the oil. But there isn't any in the oil. So I'm leaning towards a pump or clogged radiator.

To check the pump i would just unhook the upper rad hose and put a water hose in the rad and start it up and see if it pumps the water threw. then you will know foreshore.

 

[KsM715]

I would have kicked that drives rear.. STATEMENT OF CHARGES ring a bell?

That was my first thought to..... but then Ferro went ahead and drove the truck home with the same problems. If I were the driver I could understand an ass chewing and maybe a little more but Id have a hard time paying for any parts after it was driven without being diagnosed first.

 

[Boss Doug]

Back when I used to drive they had what they called a Murphy system. This would shut the truck down if it got to hot or if the oil pressure dropped to low. It also gave you time to get off the road before it would shot you down. This saved many a truck from non-truck driving steering wheel holders!!

 

[jasonjc]

My M818 came from GL with some fork holes in the radiator So when I replaced it I did the belts too. Trying to adjust the belts I pulled the water pump out and found that the impeller (plastic) was cracked. It was still working but for how long who nows. My point is pull the pump and check it.

 

[bubba_got_you]

My M818 came from GL with some fork holes in the radiator So when I replaced it I did the belts too. Trying to adjust the belts I pulled the water pump out and found that the impeller (plastic) was cracked. It was still working but for how long who nows. My point is pull the pump and check it.

[FONT=&quot]I didn’t know they where plastic! Best just to pull it and take a look then [/FONT]

 

[Flyingvan911]

Sounds like a clogged radiator. If the fluid was flowing, the radiator temp should be fairly even. Hot coolant wasn't getting down to the bottom.

 

[bubba_got_you]

Sounds like a clogged radiator. If the fluid was flowing, the radiator temp should be fairly even. Hot coolant wasn't getting down to the bottom.

but if the pump is bad it would not be flowing when hot.

 

[Flyingvan911]

True. I'm thinking the fluid might slip around enough to atleast warm the bottom of the radiator some. I could be wrong.

Good luck with the engine. Let us know what the problem is.

 

[USAFSS-ColdWarrior]

but if the pump is bad it would not be flowing

One possible failure mode that you seem to be ignoring.....

A pump with a cracked plastic rotor - like the one shown above - COULD spin properly on the shaft sometimes (when cool?), then under varying/increasing temperature or load conditions begin to slip on the shaft, thereby decreasing flow in spite of higher engine RPM. Imagine the expansion and contraction of the various parts acting like a friction clutch effect.

 

[bubba_got_you]

True. I'm thinking the fluid might slip around enough to atleast warm the bottom of the radiator some. I could be wrong.

Good luck with the engine. Let us know what the problem is.

maby but with the size of the 5ton rad you'd have to get a cat stuck in there to clog it. lol it would be more likely to be a clogged lower hose on the rad.

 

[bubba_got_you]

One possible failure mode that you seem to be ignoring.....

A pump with a cracked plastic rotor - like the one shown above - COULD spin properly on the shaft sometimes (when cool?), then under varying/increasing temperature or load conditions begin to slip on the shaft, thereby decreasing flow in spite of higher engine RPM. Imagine the expansion and contraction of the various parts acting like a friction clutch effect.

[FONT=&quot]No I understand that’s why I changed my mind and said that he should just pull it to make shore. But we where talking about how the rad at the top was hot and bottom was cool and how Flyingvan911 thought it was a clogged rad causing the problem not a bad pump. My point was that it would not be flowing when hot.
[/FONT]

 

[poppop]

I had this experience with my 1 ton Chevy dually pick-up. A couple years ago the waterpump went out and I ran the truck hot. Replaced the pump and the temp guage never worked right again. It would run up to 260 degrees and the check engine light would come on. I took it to the radiator shop several times and and the temp measured normal. The radiator went bad and was replaced and the temp guage still did not work right. Then acouple months ago that water pump came apart. When I replaced it the temp guage has worked correctly ever since. So I think something was wrong with the other pump and truck was actually running hot. I am just glad I did not burn the engine up.