B-61 Engine Cooling

[thomastractorsvc]

My B-61 is up and running and I had a couple questions on the cooling system. I searched the old posts but nothing seemed to have it all in one or all the answers.

My truck seems to only get up to 140 degrees on the gauge. Before I left on Friday I made sure all the fluids were up and I topped the radiator off to about 1/2 inch below the fill neck after about 10 miles the temp gage got close to 140 degrees it seemed to burp and a burst of antifreeze came out the cap not the overflow and then it did not leak or blow out anymore. I got parked and it was not leaking or blowing out just the single burp. Before we got ready to leave I checked the level and it was down about 1". I did not add any more and it ran fine temp only getting to just under 140 degrees on the gage. Yesterday I topped it of made sure the shutters were closed and let it run at about 1500 rpms for about twenty minutes, temp did not climb very high so I opened up the shutters and took it for a ride about 5 miles out it burped again and temp stayed at 140 degrees, I headed home and pulled up to the shop and opened the cap the antifreeze was luke warm, down about 1inch and I got out my heat gun and the temps were all constant within 5 degrees on the block and heads on both sides.

I know the cap is swollen so I am going to replace it and I was going to pull the thermostat and check it, did not know if it was stuck open or stuck shut than surging open causing the push into the radiator.

My Truck has a END 673 35933

Is this the location of the thermostat? or does mine not have one as I read in a different manual that not all models had them <<The operation and maintenance manual (1960) talks about the cooling system on pages 101 and 102 but does not show location.>>

I found the Part # for the thermostat supposed to a Mack #657GC225-P2, the manual says the thermostat is supposed to be 170 degree

The cap is supposed to be 10 psi?

[Mike]

Thomas......my END 673 P motor has no thermostat. My understanding of the setup is.......the shutters do all of the temperature issues by going through the shutterstat that has the air hose attached to open up the shutters. Now with that said.....my understanding is......that the truck will run cooler without a trailer attached. That is why the engine loads up by not working the truck. The exhaust will run richer with black exhaust pipe. I believe some trucks will run hotter, depending on the closeure of the shutters. This subject has come up before but not to this extint. I hope someone else will elaborate on this subject soon.

Does your shutterstat get hot air from the engine? Does it leak air? if the engine gets up to say.....160 degrees then the shutterstat will open the shutters just enough to allow the temp to maintain say 160 degrees.

mike

[thomastractorsvc]

Mine also has a shutterstat but the shutter actuator seals are rotted out so I removed it until I can find some repair seals, no luck yet. I put a plug in the shutterstat where the hose would come off so it would not leak air. I looked at where the upper radiator hose hooks and I don't see where a person would take off anything to install a thermostat.

What is the difference with the END 673P vs END 673?

[Mike]

Mine also has a shutterstat but the shutter actuator seals are rotted out so I removed it until I can find some repair seals, no luck yet. I put a plug in the shutterstat where the hose would come off so it would not leak air. I looked at where the upper radiator hose hooks and I don't see where a person would take off anything to install a thermostat.

What is the difference with the END 673P vs END 673?

I know what you mean. The upper hose goes into a housing that would appear to have a thermostat, it is big enough to have several. I went to my local Industrial Rubber Company and showed them the unit I had to work with and they measured the ID and got me the diaphram I needed. It does not leak now. The engine still has to develop enough heat to operate the shutterstat. Then the shutters will open accordingly. Barry sells the thermostat and I bought one but I cannot find where it goes either. I think the gas engines accommodate the thermostat instead of the diesels.

The difference of the END P vs. the END is a smaller wrist pins with the P engines.

mike

[thomastractorsvc]

I talked with Watts today, the gentleman I spoke with said that if the truck requires a thermostat it goes on the upper water manifold and it will have 4 bolt removable housing. I guess if it does not have that housing like mine, than it is operated off the shutterstat. If you don't have one either you don't need the one you bought.

[thomastractorsvc]

BTW What PSI radiator cap are you running on your truck?

[Mike]

I talked with Watts today, the gentleman I spoke with said that if the truck requires a thermostat it goes on the upper water manifold and it will have 4 bolt removable housing. I guess if it does not have that housing like mine, than it is operated off the shutterstat. If you don't have one either you don't need the one you bought.

I'm with ya on this. My engine does have the 4 bolts on top where the upper hose goes in to the maniflod. But I could not pry off the lid after taking the bolts off. It looks like a machine finish and cannot come off. That statement is true as to what you heard by not having the bolts no thermostat. My book shows a thermostat with the END673 engines but don't know if it ment all 673's or not.

mike

[Mike]

BTW What PSI radiator cap are you running on your truck?

I found a 7 lb. cap at NAPA truck center couple of years ago that look as close as I could find to mine and used that.

mike

[Maddog13407]

the difference in a 673 and 673P is the intake manifolds. the P engines had the split intake manifolds ORIGINALLY just like a 711 did. that's not sayin they still do after all these years. the 673 had 180 hp and I think the P engine has 187hp. the engine in the picture does not have a thermostat. hard to tell because the pic is cut off at the top where it would go.the engines without a thermostat the temp would be controlled with the shutterstat and shutters. the engines with the thermostat had 3 or 4 bolt s holding the housing on and the thermostat was under them where the top radiator hose attaches to the block

[Freightrain]

Just by the picture I can tell it is not a P engine by the shape of the intake. Too bulky looking compared to mine which is a split design.

[Maddog13407]

yup, that could be a P engine but someone put an older style aluminum 53-58 intake manifold on it

[thomastractorsvc]

Its a 1959 year model, but was made in December of 1958 so probably original manifold as that is a picture of my trucks engine, I was looking for a picture that showed the left side of the engine that's the only one I could find from over a year ago.

My phone does not have a data plan so I use my wifes phone but she was at work this morning.

[theakerstwo]

That should have a 6 lb cap on it and the thermostat housing if it has one will have three bolts in it going downward and the late models had four bolts going to the back of the engine.

the cover that holds the thermostat id part of the neck for the upper rad hose.You can install a thermostat housing on it if you want.The common HP for a end673 is 170 and a p would be 187 hp.That has no oil cooler so it is a early engine.

[thomastractorsvc]

I am fine with not having a thermostat, I was trying to trouble shoot for the burp, I could only find a 7lb cap also, it had a 4lb on it and the gasket was swollen so I figured it may have been sticking and not releasing like it should. I just went for a 20 mile drive and it only got up to 120 with no burbs so hopefully it was just the cap. The antifreeze did make a mess that is hard to wash off the new paint on the inside of the engine and on the side panels, I will wash them again tomorrow before I put them back on.

[Mike]

Too bad the makers of antifreeze can't make it not leave a stain. What I mean is, make it where it does not leave the paint a dull finish as to where ever it runs.

mike

[HarryS]

I guess I have the same problem with my '60 B-61 673. I have a thermostat and nowhere to put it. At first I thought the temperature gauge wasn't working as it did not move after 20 minutes of fast idle. After checking with a non contact the temp was only 105 at all points. The shutter air cylinder leaks and the air turned off, also the pivot point for opening and closing the shutters is binding. I think it is worn. Is there a replacement or rebuild for the air cylinder? Harry

[thomastractorsvc]

I saw a rebuild kit on ebay about a month ago but was unsure if it would fit my actuator and did not want to gamble for the price, when I was talking with Watts yesterday they said that they can get the original style actuators but they are expensive. The one they sell for the R & DM can be used but you would need to modify the linkage.

I am going to try and find a place locally to see if it can be rebuilt.

[mackman55]

The burbs is just air bleeding out. I had the same problem with my 1955 B-61 I put a new cap on and that took care of it

[Freightrain]

There is not alot to those air cylinders. I pulled mine apart to clean the sludge out. Just a leather seal if I recall.

[thomastractorsvc]

I took mine apart and the seal is torn. I am going to take it to a hydraulic shop to see if they have the parts or can make it.

I think the water pump is not pumping as I flushed the radiator and block this morning and I noticed that there was no circulation in the top of the tank. I disconnected the small line that runs up to the water manifold and started the truck and there was no pressure just the same pressure with the truck off, that would explain the burps as hot water makes it way back to the radiator. While I have it down I am going to have the radiator done too, hopefully that should cure the coolant system.

[thomastractorsvc]

The water pump bearings are shot surprised it was not leaking, there was a lot of play and drag, probably 2 miles short of failure. Dropped off the radiator supposed to be ready some time tomorrow.

Searched the threads and found a Mack part number 316GC184NX, called the local Mack of course not available and they would have to do a search contacted, contacted Ballard Mack in Mass, they had one. I had also called CARQUEST and NAPA, the kid at NAPA said they had one for a B-67 and a B-42 but nothing for a B-61, I said what if I bring mine to compare he said there was no picture, the guy at CARQUEST said give him a few minutes and he called and said he found three styles so I headed over and they had one but not in stock locally so should be in by Friday. Its a REMAN part number 701, I will get the manufacture and post it. Was $104.00 plus tax and freight + $40 core.

[thomastractorsvc]

Just got the water pump new casting so don't need all the plugs it is a Haldex reman Part Number RW2001X

CARQUEST and NAPA have them probably can get from others if you can find a knowledgeable parts guy. NAPA has it listed on line for $96 + $37 core

I tried NAPA first they were clueless once I got the part number it shows up on the online. Oh well! could have saved $8 bucks

[Mike]

Just got the water pump new casting so don't need all the plugs it is a Haldex reman Part Number RW2001X

CARQUEST and NAPA have them probably can get from others if you can find a knowledgeable parts guy. NAPA has it listed on line for $96 + $37 core

I tried NAPA first they were clueless once I got the part number it shows up on the online. Oh well! could have saved $8 bucks

Thomas,

Those water pumps can be rebuilt. It's just a pressed in bearing that you will need. If the housing is not destroyed then you may want to reconsider looking into your local bearing shop to set you up on this matter. These really are a simple unit.

mike

[Maddog13407]

always thought the waterpumps were the same for the 673, 711 and 675's myself.

[thomastractorsvc]

They showed three different water pumps for the Mack 6 cylinders depends on the length of the shaft and how many pulleys it has. Mine was the shortest with a two belt pulley, all buttoned up and back on can now see movement in the radiator.

Mike it was not worth the hassle to track down bearings and if it had possible shaft damage since it had the lube fitting on top and was dragging and lots of end play, then try and make three gaskets and it comes with a warranty so that's worth something.