M-37 exhaust and intake manifold design

[Joe Bertram]

Good evening, been working on our M56-B1 M-37 style contact maintenance truck. After getting the truck running after sitting several years we found a sizeable crack in the front of the exhaust manifold. Ordered a new matched set from vintage power wagons including studs. Long story short after breaking studs and some extractors I'm left with 2 holes that are sloppy at best, they are definitely in water jacket. What sealant do I use on the good studs? What kind of helicoil product do I use on repairs for the 2 holes? And what layout for the brass washers, brass nuts, locking nuts? Thank you guys

 

[ODAddict]

On our recent rebuild, we used "Permatex Thread Sealant with PTFE."

Can't help with the helicoil situation...never had to use one.

We put the 4 brass spacers (2 each) on the exhaust manifold studs at each end. The black clamping washers hold both the intake and exhaust manifolds together. Photos attached.

Hope I did it right; the manuals are a bit unclear, but I had an accomplished machinist assisting me.

 

[Joe Bertram]

On our recent rebuild, we used "Permatex Thread Sealant with PTFE."

Can't help with the helicoil situation...never had to use one.

We put the 4 brass spacers (2 each) on the exhaust manifold studs at each end. The black clamping washers hold both the intake and exhaust manifolds together. Photos attached.

Hope I did it right; the manuals are a bit unclear, but I had an accomplished machinist assisting me.

Im working on it as we speak, uses a product called time-sert and had awesome luck. I'm bolting the manifold up now used permatex gasket #2 on the studs. I wondered about the conical brass washers if the nut was supposed to go taper out into the washer or go on like a castle nut

 

[ODAddict]

If I understand your question, the nut should go on like a castellated nut. I'm getting close to the limit of my competence, though, so if someone else can confirm or correct, please do.

 

[Joe Bertram]

If I understand your question, the nut should go on like a castellated nut. I'm getting close to the limit of my competence, though, so if someone else can confirm or correct, please do.

Update on exhaust manifold nuts, talked to vintage power wagons folks and they advised nuts taper fit into the brass convexed washer taper down

 

[87cr250r]

I'm a Helicoil fan. I think Timesert uses their high price as an advertising point... However, in this special case where the threads need to seal I would suggest the Timesert with sealant. My favorite general purpose sealant is Loctite 577 but that may not be accessible to everyone. Don't use 567, I hate that stuff.

 

[Joe Bertram]

I'm a Helicoil fan. I think Timesert uses their high price as an advertising point... However, in this special case where the threads need to seal I would suggest the Timesert with sealant. My favorite general purpose sealant is Loctite 577 but that may not be accessible to everyone. Don't use 567, I hate that stuff.

They definitely worked as advertised, albeit a little pricey but what specialty tool isn't. Kit with drill, tap, countersink tool and insert tool along with 5 time serts for a hundred bucks was worth it for this project

 

[87cr250r]

Helicoil kits used to be $25 but gained on Timesert considerably recently.

However, I prefer Helicoil due to the variety of alloys available (not from your local hardware store). They have Nitronic 60 inserts that prevent galling when working with stainless steel fasteners and they have PTFE coated inserts that prevent galvanic corrosion when installed in aluminum. And once you have the tap the inserts are inexpensive.