M939 series radiator tank torque spec.

[Gunzy]

I have looked in the TM and can only find information for changing the radiator as an assy. I have a truck that is leaking at the gasket for the left tank. I have new gaskets but need a torque specification for the 40 nuts/bolts that mounts it. The TMs don't show anything for that as that is not a field or depot service procedure. With the gaskets being cork I don't want to over tighten them and still have leaks. Or if some one can tell me exactly where to find the spec would also be nice. I thought about checking with a radiator shop but doubt they would know unless they are working on these radiators. I appreciate any help.

 

[Gunzy]

Wow, nobody has this info? I must ask some tough questions as this isn't the first time I have asked for info and received "0" response. Surely someone knows the answer. I guess my next step is to contact the contractor that built the radiators.

 

[Tow4]

Aren't the fasteners bolts with nuts? You can look up the torque spec for the grade and size of bolt and go from there.

 

[tbar123]

When I rebuilt my radiator I just put the impact on low and zipped them in until they made contact. Then went back with ratchet and added 1/4 turn no leaks.

 

[Swamp Donkey]

I see this thread never got an answer so I'll add to it for folks that run across it in the future, like myself.

Indiana Heat Transfer Corporation is the manufacturer of the M939 radiators. I sent them an email yesterday requesting the torque value of the bolts and the sealing process that is being used.

The torque value for the tank bolts is 15 ft-lbs.

Cork gaskets are installed dry. Any sealant used can cause problems with the torque process, allowing the gasket to squish out in places which affects sealing. Sealants can cause issues later after heat cycles have caused expansion and contraction of the sealing surfaces. Friction is necessary to keep the gasket in place. Over time sealants will allow the gasket to work it's way out.

This is the problem I'm dealing with now. My driverside tank had been removed by someone due to a leak. The old gasket was reused and a sealant was added. This allowed the gasket to slowly work it's way out causing a leak.

I'll also add this for those replacing tank gaskets. The bolt flange on the tank is likely to be deformed. This should be flattened out, cleaned and dried to ensure a good sealing surface is present. The radiotor flange should also be clean and dry.

If you want to make your own gaskets, you can get a roll of Felpro 3007 cork/rubber gasket material from most automotive stores. It measures 36"L x 18"W and is 1/8" thick.

While they didn't give me a torque sequence, the one below is from Freightliner for their top mount tanks. The main thing is to start from the center and work your way to the ends. The torque values in the screenshot are not for our radiators. I'm only showing the torque sequence here.

 

[74M35A2]

A-1 as always SD. Gunzy, you say you have replacement gaskets. If not generic sheet that you cut, what was your source? Thanks.

 

[gstirling]

I see this thread never got an answer so I'll add to it for folks that run across it in the future, like myself.

Indiana Heat Transfer Corporation is the manufacturer of the M939 radiators. I sent them an email yesterday requesting the torque value of the bolts and the sealing process that is being used.

The torque value for the tank bolts is 15 ft-lbs.

Cork gaskets are installed dry. Any sealant used can cause problems with the torque process, allowing the gasket to squish out in places which affects sealing. Sealants can cause issues later after heat cycles have caused expansion and contraction of the sealing surfaces. Friction is necessary to keep the gasket in place. Over time sealants will allow the gasket to work it's way out.

This is the problem I'm dealing with now. My driverside tank had been removed by someone due to a leak. The old gasket was reused and a sealant was added. This allowed the gasket to slowly work it's way out causing a leak.

I'll also add this for those replacing tank gaskets. The bolt flange on the tank is likely to be deformed. This should be flattened out, cleaned and dried to ensure a good sealing surface is present. The radiotor flange should also be clean and dry.

If you want to make your own gaskets, you can get a roll of Felpro 3007 cork/rubber gasket material from most automotive stores. It measures 36"L x 18"W and is 1/8" thick.

While they didn't give me a torque sequence, the one below is from Freightliner for their top mount tanks. The main thing is to start from the center and work your way to the ends. The torque values in the screenshot are not for our radiators. I'm only showing the torque sequence here.

View attachment 703461

SD
I have a theoretical question on the use of sealants as you addressed above and hoping you might have some advice. why would use of gasket sealants on the radiator end tanks be any different than say on an oil pan? i'm about to open up my radiator to fix some leaks (hoping it just needs new gaskets) and normally would have used gasket sealant to help hold this kind of big gasket in place and "help" the gasket fill any dips in the mating surface. your info above has me questioning mixing gaskets and sealants??? any advice on when there a time to use both and time not to (as in this application??). maybe based on hi torque use vs low torque mating parts????
thanks!!!

 

[silverstate55]

My guess would be expansion/contraction values of gasket material vs bolts/nuts vs radiator parts…but my guesses are usually way off.

 

[Jbulach]

SD pretty well covered the reasons not to use sealers on cork gaskets. The only place you want a small dab of sealer on any cork gaskets is where muti-piece gaskets butt together, or slightly misaligned joints in parts under a shared gasket. If you must have something to hold a gasket in place for assembly use a hi-tack adhesive.

 

[Swamp Donkey]

SD
I have a theoretical question on the use of sealants as you addressed above and hoping you might have some advice. why would use of gasket sealants on the radiator end tanks be any different than say on an oil pan? i'm about to open up my radiator to fix some leaks (hoping it just needs new gaskets) and normally would have used gasket sealant to help hold this kind of big gasket in place and "help" the gasket fill any dips in the mating surface. your info above has me questioning mixing gaskets and sealants??? any advice on when there a time to use both and time not to (as in this application??). maybe based on hi torque use vs low torque mating parts????
thanks!!!

Gasket maker (gasket sealer, etc.) is exactly what it is called. It makes a gasket where there isn't one. It creates a gasket once it is cured. Gasket maker is way overused in general and is usually excessively applied. You would never use two stacked gaskets, but that is what you're doing if you use gasket maker on a gasket, when not specifically called for.

I'm only speaking of cork gaskets here. A cork gasket needs to be anchored to one of the mating surfaces. This is usually going to be the surface of the piece being removed, so the radiator tank in this example. Notice I said anchor, not seal. The gasket is doing all the sealing. Trying to anchor with gasket maker/ sealant will cause the gasket to slip over time.

I've been using 3M 77 Multipurpose Adhesive spray to anchor gaskets forever. Spray a light coat on one side of the gasket and apply gasket to the removable mating surface. Let the adhesive cure, then reinstall tank. Use the proper torque specs. The flanges on the tank and radiator are thin and overtightening will only cause leaks.

Proper prep of the mating surfaces is always important. If the mating surfaces have imperfections that can't be removed, like pitting, then gasket maker can be applied. Use a light skim coat to fill the imperfections then run a straight edge across the surface to remove everything except what is being used as fill. Let this dry completely before installing the gasket.

Now if you use the Felpro gasket roll in my previous post then you'll be cutting a one piece gasket. No gasket maker should be used. Lay the tank on the gasket material and trace around the tank flange. A 1/4" punch can be used to make the holes. Use the spray to anchor a new gasket and install the tank.

The original gaskets are sometimes available through surplus and these are sectioned in pieces. You'd follow what Jbulach said and only apply gasket maker at the joints. You want just enough to seal the joint with a very light coat on the gasket surface right over the joint.

There are a 100 different types of gaskets of different materials and designs out there these days. I'm only talking about cork here. Gasket maker and cork, unless specifically called for, is asking for trouble down the road. Anchor the gasket and let the gasket the job as it was designed.

 

[gstirling]

Gasket maker (gasket sealer, etc.) is exactly what it is called. It makes a gasket where there isn't one. It creates a gasket once it is cured. Gasket maker is way overused in general and is usually excessively applied. You would never use two stacked gaskets, but that is what you're doing if you use gasket maker on a gasket, when not specifically called for.

I'm only speaking of cork gaskets here. A cork gasket needs to be anchored to one of the mating surfaces. This is usually going to be the surface of the piece being removed, so the radiator tank in this example. Notice I said anchor, not seal. The gasket is doing all the sealing. Trying to anchor with gasket maker/ sealant will cause the gasket to slip over time.

I've been using 3M 77 Multipurpose Adhesive spray to anchor gaskets forever. Spray a light coat on one side of the gasket and apply gasket to the removable mating surface. Let the adhesive cure, then reinstall tank. Use the proper torque specs. The flanges on the tank and radiator are thin and overtightening will only cause leaks.

Proper prep of the mating surfaces is always important. If the mating surfaces have imperfections that can't be removed, like pitting, then gasket maker can be applied. Use a light skim coat to fill the imperfections then run a straight edge across the surface to remove everything except what is being used as fill. Let this dry completely before installing the gasket.

Now if you use the Felpro gasket roll in my previous post then you'll be cutting a one piece gasket. No gasket maker should be used. Lay the tank on the gasket material and trace around the tank flange. A 1/4" punch can be used to make the holes. Use the spray to anchor a new gasket and install the tank.

The original gaskets are sometimes available through surplus and these are sectioned in pieces. You'd follow what Jbulach said and only apply gasket maker at the joints. You want just enough to seal the joint with a very light coat on the gasket surface right over the joint.

There are a 100 different types of gaskets of different materials and designs out there these days. I'm only talking about cork here. Gasket maker and cork, unless specifically called for, is asking for trouble down the road. Anchor the gasket and let the gasket the job as it was designed.

thanks for that info!!!! perfect.