F-134 Flywheel Bolt Question...

OKCM38CDN · Post by **OKCM38CDN** » Mon Jun 02, 2014 8:53 pm

I pulled the power train on my M-38A1 (it is under full teardown for restoration) and then separated the engine from the bell housing and found I needed to pull the fly wheel to mount the engine on an engine stand...

In the process one of the tapered dowel bolts pulled out... I know I will need to replace this with a regular bolt...

My question is will I need to pull / loosen the crankshaft to do this... looks like it at first glance, I just want to be sure...

Thanks in advance...

Bretto · Post by **Bretto** » Tue Jun 03, 2014 6:05 am

If I remember correctly, you can get to those by removing the rear crank bearing cap.

skyjeep50 · Post by **skyjeep50** » Tue Jun 03, 2014 7:40 am

Yes, you can remove the bearing cap and have clearance to replace the flywheel bolt. I had to do the same thing on a rebuilt L-134 motor I bought for my M38.

Post by **wesk** » Tue Jun 03, 2014 8:50 am

In the process one of the tapered dowel bolts pulled out... I know I will need to replace this with a regular bolt...

Unless you have mixed a flywheel with a different crank you retain the two tapered dowel bolts. If the crank and flywheel are not factory original to each other then a dowel bolt kit must be purchased and a pair of accurately drilled match holes must be drilled through the crank and flywheel to accept the special stepped dowel bolts.

OKCM38CDN · Post by **OKCM38CDN** » Tue Jun 03, 2014 9:26 am

Wes,

I pulled the flywheel with my hands, No tools used other than pulling the nuts... Wiggled the flywheel back and forth and this bolt came out with the flywheel...

it was wallowed out and pulled right thru the crank flange... the other tapered bolt is doing the same thing, it is about half way thru the flange or appears to be...

I was figuring on just getting a proper sized Grade 5 bolt and replacing the one dowel...

Was not planning on tearing the engine down... was told it had just been rebuilt...

But after seeing some of the things I have maybe a good inspection is in order...

I will try to post photos later today...

BTW: this M-38A1 is the one I purchased two years ago from the gent in Wisconsin...

I have a rebuild thread going...

billybob · Post by **billybob** » Tue Jun 03, 2014 12:59 pm

Is it possible they used the smaller tapered dowel when it should have been the straight 9/16 dowel? The crank and flywheel I'm using takes the straight 9/16 dowel. [ I'm calling it 9/16 because that is the closest measurement I could get.] I got the two dowels from Peter Debella - NOS.

Xamon · Post by **Xamon** » Tue Jun 03, 2014 1:58 pm

if I understand right this is part 8328311 Bolt, dowel, 3/8-24NF-3X3 3/8.
At least according to the parts manual for the m38a1.

Post by **wesk** » Wed Jun 04, 2014 12:30 am

The stock tapered dowel bolts are 7371231 (WO# 632156). These use 3/8-24 nuts jsut like the other 4 plain bolts.

The straight shouldered dowel bolt is 1/2"-20 threads with a 9/16" dia. shank. They are 7371232 (WO# 116295)

tHE BOLT Xamon refers to 8328311 is the 3/8-24 dowel bolts for the bell housing.

oilleaker1 · Post by **oilleaker1** » Wed Jun 04, 2014 5:23 am

It sounds like a previous owner put in the wrong dowel bolts for sure. I've been able to change or install the flywheel bolts with just the oil pan pulled. Hope you get lucky and the crank flange holes are still ok for the correct straight shank bolts! John

OKCM38CDN · Post by **OKCM38CDN** » Wed Jun 04, 2014 6:25 am

In my SNL it lists the tapered dowels. However a PO could have used a different Crank shaft... the bolt that is left in the shaft does not seat properly...

I spent the day yesterday taking the transfer case / transmission apart to get them soaking in degreaser in prep for rebuild...

I will take photos today and post them...

Xamon · Post by **Xamon** » Wed Jun 04, 2014 6:37 am

that is odd Wes, the number you give is the one listed for the flywheel in the m38 manual, the one I gave was listed for the flywheel in the m38a1 manual. Either way the point I suppose is that the parts manuals are available for download here and contain a complete list of all the bolts with the correct sizes.

Post by **wesk** » Wed Jun 04, 2014 8:48 am

Xamon,
Look a little closer at that page in the M38A1 manual. The bolt you ID'd 8328311 is 2/3 rds the way down page 38 and is clearly labeled Bolt, dowell 3/8" but you are not paying attetnion to the next higher assembly above it which is HOUSING, flywheel assy.. You missed the Flywheel assy 1/3 rd down that same page which lists Pin, Dowel tapered.

The assembly underlined in red is the core of this discussion.

Xamon · Post by **Xamon** » Wed Jun 04, 2014 4:50 pm

Ah that would be it, I am occasionally accused of being blind despite 20/20 vision, mostly by my wife.