Monday, May 14, 2012

Engines...Door Number One: CJ2A or 3A or...Military?

I've got two complete engines that spin freely sitting on my garage floor at the moment.  One appears to be a postwar CJ2A (maybe 1947) and the other is a GPW wartime engine (mid 1942).  Both have positive attributes as well as issues that need to be addressed.  I figured since the CJ engine was strategically positioned in the middle of my floor, I would begin with that one.  It is, incidentally, the engine that I pulled out of the current jeep I am rebuilding.  Although it isn't original to the jeep, it was with it when I bought it.
I began with removing some of the various bolt-on components on the block.  With a large portion of surface area now exposed, I was able to get a combination of hand grinder wire wheel, wire brushes of assorted sizes, and flat headed screwdrivers across most of it.  Between the layers of dirt and grease, the paint came off quite easily.  I promptly coated it with the rust prohibitor/converter chemical and then primed the upper portion of the block.  I will do the bottom portion (oil pan) when I put the block up on an engine stand.  The head is just sitting on the engine, not bolted on, to try to keep the dust and dirt out.
CJ2A pre-clean front.

CJ2A side.

CJ2A rear.

CJ2A side.

CJ2A post clean.  Note the oil pan has not been touched, and the head is just sitting in place. 
This head will not be used with this block.


With it mostly cleaned, I could then actually see where the problems are!  The exhaust manifold's bolt ears have been broken off where the exhaust pipe will connect to it.  That stinks.  Other than that, it looks pretty good.  I have a second manifold laying in the garage, unattached to an engine, but it is cracked.  The exhaust manifold get the brunt of high temperatures, so, unfortunately, it is common to find them broken.  I have yet to make my mind up what I am going to do with it.  Cast iron can be difficult and sometimes impossible to repair. 
Location of the broken bolt ears on the exhaust manifold.
The other issue I discovered is that the exhaust valve on cylinder #4 is a bit sticky.  It will move into the open position, but it will not drop back to the closed position.  I discovered this when I removed the side cover so I could inspect all of the valves and adjust them if necessary.  I was spinning the crank nut in the front of the engine watching all of the valves operate.  Something looked odd, though, but I couldn't figure it out.  Well, the oddball was #4 exhaust not closing!  I could tap it with a rubber mallet and it would shut.  Then, as I rotated the crank, it would open and then not close again.  Since it will move, I am hoping that it just has a bunk of gunk that needs cleaned off of the stem inside the guide.  Might as well address it now, though.

In a perfect engine, the valve locks are removed and the valve will slide out without resistance.  This valve was not budging.  It is well documented that on side valve engines (which is what this is) the valves tend to get gunky with exhaust and old gas residue and such.  After a lot of agony where I had to exert an over-abundance of patience on my part, the valve was removed.  Throughout the process, I even contacted one of my fellow jeepers for some advice.  Thanks, Phil!

Once the valve was removed, I inspected it and it seemed like it was fine.  Nonetheless, I cleaned it up and then turned my attention to the valve guide.  The inside of the valve was pretty dirty with carbon and gunk.  I used some carb cleaner and my rifle bore cleaning rod.  Pretty creative on my part, I think!  The valve guide isn't quite shiny clean you can eat off of it, but when I dropped the valve back in, well, it fell right into place without any resistance.  Nice.  Since I am here, I might as well go ahead and clean the other seven, right?  C'mon on over, Jeff, and get your mits dirty.
#4 Exhaust Valve (far right) is a bit sticky. 
The spring should have compressed it back down to the tappet.

A look from the top...the valve remains open when it should be closed!

Just a close-up of #4 exhaust.

Step one in removing the valve:  use the spring compressor to expose the two crescent shaped locks.
After a day long struggle (and a consultation from a fellow jeeper), this PITA popped out!

After cleaning up the valve and the valve guide, the valve slid back into the guide without any resistance.

I let go of the valve and gravity took over!  Perfect.
 (Jeep Police do not critique; I still have to assemble the spring, locks and adjust the tappet for a better fit.)
I am glad that I journeyed forward and removed all of the valves, one at a time.  Turns out that they all needed a decent cleaning, especially the exhaust valve on cylinder number 2.  That guy turned out to be almost as gunked up as the trouble valve in #4!
All of the parts for a single valve.  If memory serves me, this was the intake valve of the #2 cylinder.  From L to R, the valve, valve spring, spring plate, and the valve locks.  The locks sit in the inset of the bottom of the valve stem and the spring plate sits over the top of the locks, keeping them in place.  The spring sits between the top of the engine block and the the spring plate, always pushing the valve closed.
Oh, and on a side note, while I was first spinning the crank nut I was using a plumber's pipe wrench.  Well, it slipped off the nut and my left hand went crashing into the water pump's pulley.  My middle finger is black and blue...not broken...but hurts A LOT!  I almost passed out from the pain.  Yes, I am a sissy.  Anyhow, it knocked some sense into my brain- I am now using a super sized socket (the same one I used to loosen the impossible nut on the transfer case) and it is SO MUCH EASIER and the chances of me hurting myself again have greatly diminished!

While I was spinning the crank nut, I noticed A LOT of debris falling out of the timing hole in the bellhousing.  I removed the bellhousing to clean it out.  What I found amazed me...I think it is an old mouse nest.
A lot of rubbish from a pack rat!

Besides all of the debris, this is a good view of the pressure plate that holds the clutch in place against the flywheel.  Eventually, these parts will be removed, cleaned and replaced as needed when jeep #2 gets on the assembly line.
There was definitely more in there than I expected!  On the plus side, while I cleaned up the underside of the bellhousing, I found another gorgeous F mark!  Turns out, the bellhousing is a genuine Ford part.  At this rate, the jeep is going halvsies between Ford and Willys.  Once everything is put together, though, all of the outside visible parts will be Willys and Ford will make it move.
There is a quarter-hole on the left hand side of the bellhousing's equator.
 Although it is stamped sideways, the script F is clearly visible-GPW Bellhousing!
Unless the bellhousing on the GPW motor is a Ford part, I will switch the two around.  As for the clutch and the pressure plate, I will clean those up and replace as needed when jeep #2 gets going.  The other switch I want to do is when I rebuild the distributors.  The CJ2A engine has a December 1942 distributor in it, while the GPW engine has a postwar distributor.  As for now, I am going to button this engine up, do a compression test on it and then paint it Willys OD (green) in an effort to camouflage the fact that it was manufactured during the post-war years.

EDITED:  as of 4:42PM 5/14/12

I've been doing some research on this engine block.  (Both kids are napping, but I am still a bit under the weather to get nasty in the garage.)  I've been trying to track down the serial number of this engine block.  All I have confirmed is that it is a later version of the 641087 blocks...which means it was built after 1950.  The stamped serial number is present, but half of it was so lightly stamped that it is not readable (yet!).  The civilian and military engines of this time period were identical in appearance and the ONLY differentiating marks was the stamped serial numbers.  Civilian engines started off J3xxxxxx (x's being numbers) and the military engines were either MCxxxxxx or RMDxxxxxx.  MC was the original engine and RMD was a replacement engine.  At the moment, all I can confirm is 3357- the last 4 digits.  At first, I thought I saw the center of an "X", but that was before I did my research.  Now, I cannot confirm it, but I am leading towards the center of the "X" actually being the center of an "M".  Are you entering a blissful jubilee like I am?  Of course you aren't.  One, you aren't a jeep geek; and two, you want proof.  And better proof than the delusional sightings of a medicated mind!

Now why all of the fuss you ask...well, if it is an MC or RMD engine, then it was originally installed in a military jeep.  Perhaps it was a replacement block for this jeep while it was still in the service?  I certainly have found a plentiful amount of Ford parts on it, already.  Motorpool work at its finest!

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