WARNING!!! Rebuilding GPW/MB Engines

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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1943Willysgpw
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by 1943Willysgpw » Fri Mar 02, 2018 6:14 am

17thAirborne wrote:
Fri Mar 02, 2018 6:08 am
Great discussions all and a few barbed retorts to ice the cake, but does anyone else have any things to offer in terms of advice to the novice engine builder so that the various pit falls might be avoided to a certain degree? I appreciate all the L134 helpful comments, and for those of us who will be doing more of these in the future, keep the advice coming.

thanks
Sorry. Just realized something. I did not mean to hijack your thread. Thanks everyone. Oh, this thread has help greatly. But now I have to pull my GPW pan and look at the orientation of the rod caps. :oops: :lol:
"None of us are as smart as all of us"

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by 17thAirborne » Fri Mar 02, 2018 7:00 am

1943Willysgpw wrote:
Fri Mar 02, 2018 6:14 am


I did not mean to hijack your thread. Thanks everyone. Oh, this thread has help greatly. But now I have to pull my GPW pan and look at the orientation of the rod caps. :oops: :lol:
np, just looking to keep the engine rebuild comments flowing :wink:
Oz

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Joe Gopan » Fri Mar 02, 2018 7:58 am

And do not shorten the two rubber packings that go to the MB/GPW rear main bearing cap, pay attention to the length of the bolts that go across the front of the oil pan and if the fuel pump lobe on the camshaft is scored, best install a new cam.
And when installing the engine, make sure the Accelerator Pedal Cross Shaft Bracket and its' lever are correctly installed on the back of the block. :wink: It does happen frequently and causes a lot of work.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by 17thAirborne » Fri Mar 02, 2018 9:16 am

Great comments gents! 8)
Oz

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Joe Gopan » Fri Mar 02, 2018 7:06 pm

And remember,
All the stamped numbers on MB/GPW rods and caps are supposed to be installed on the same side.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Marty, SoCal » Sat Mar 03, 2018 5:17 pm

If you are using a later model crankshaft with the bolted on counterweights, make sure you are using socket head 1/8" pipe plugs on the inner oil gallery plugs, the original square headed one will hit a counterweight on the newer style crank. Note that most late cranks won't have the oil gallery drilled to feed the oiling to the chain drive.

When assembling the crank to the block, you should be able to turn the crankshaft by hand with the main caps torqued and the rear main seal installed. (no rods and pistons) There are some rubber "Victor" brand seals that will bind the crankshaft and cause the rear main to burn up from overheating. It should take less than 40 ft/lbs on a torque wrench to turn an engine over with the rods and pistons with rings installed.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by 17thAirborne » Sun Mar 04, 2018 5:59 am

Super comments...keep them coming!
Oz

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by artificer » Sun Mar 04, 2018 10:10 am

Not sure if it was mentioned earlier but any ring ridge @ the top of the cylinder on any engine [not only Jeep] should be eliminated before removing pistons & measuring up the bore.
Loaner tool available from a number of auto parts suppliers in the US.
Broken or damaged ring lands can result if the ridge is not removed.
When new rings are fitted the top ring will break, most likely on startup.
The top of the bore will be a worn semi circular fillet shape & the new ring edge will be square.
The conditions above don't work together & primarily why the ring ridge needs to be gone.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by artificer » Sun Mar 04, 2018 11:23 am

LUC can't help but criticize others offering valuable information. What is he trying to prove!
His last post didn't add value but it did show his very patchy experience, learning & knowledge.

The top of the bore is not where one should be setting anything up.
The unworn bottom of the bore is always central & where one should be working from & measuring.
That is something we can all learn & is a point to remember.

Intimately knowing Jeep engines, as I have from the 1960's on, will know the pistons & con rods can be removed from underneath.

Not everyone is like wealthy LUC & doing full rebuilds.
Many will possibly be re-ringing pistons & re-bearing con rods without the crankshaft being removed.

LUC needs to move on with his personal grudge match resulting from when I woke up to his garbage a couple of years ago & cut off ongoing contact. Then personally nasty emails started. His emails are blocked & I don't open or answer any of his PM's.

LUC needs to stop screwing up threads like this, that are not his & let others do what they do best.
Listen & help those asking for information to get their repairs right & keep their Jeeps running.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by dinof » Sun Mar 04, 2018 1:04 pm

Did I read this wrong? isn't it always protocol to check & remove a ridge on the top of the cylinders if there is one? You don't want the top ring hitting it for sure.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Joe Gopan » Sun Mar 04, 2018 1:06 pm

Depends on why the engine is being worked on.
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by artificer » Sun Mar 04, 2018 1:36 pm

Removing rods & pistons through the top the ring ridge should always be removed.
Replacing pistons & rods no matter which direction/way the ring ridge should be removed.
Anything else is mis-information & incorrect.
And the usual one liners don't cut the mustard.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Johnr » Sun Mar 04, 2018 10:22 pm

I believe this is the updated universal jeep page referenced.

Cheers
John
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Joe Gopan » Mon Mar 05, 2018 3:03 am

And the above is what Willys factory trained Jeep Technicians have subscribed to since the beginning. The specifications are easy to follow but may not be easy for the do it yourself beginner. It still requires the use of special tools and precision measuring instruments. Engine rebuilding skill is a must.
2011 MVPA PIONEER AWARD - MVPA #1064
HONOR GRAD-WHEELED VEHICLE MECHANIC SCHOOL 1960 - US ARMY ORDNANCE SCHOOL(MACHINIST) ABERDEEN PG 1962 - O-1 BIRD DOG CREWCHIEF - 300,000+TROUBLE FREE M-38A1 MILES
LIFE MEMBER AM LEGION-40/8-DAV
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Re: WARNING!!! Rebuilding GPW/MB Engines

Post by Marty, SoCal » Mon Mar 05, 2018 7:44 am

If you can find some you can use a + .001" half and a std. half to take up .005", etc. to dial in the clearance.

For many popular engines they are still available either aftermarket or from the OEM.
43 Ford GPW 92098
53 Dunbar Kapple M100
Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
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