Rebuilding the M35A2 Multifuel
Its nice to finally return some of the favors and advice that the list has given me over the years. Following is a list of suggestions, observations I'm accumulating while rebuilding my M35A2 multifuel. While I hope this makes your learning curve easier than mine, of course I can not take responsibility for your results. Research every step of the way, take your time, buy lots of pizza and beer , especially for any expert consultants, and mostly have fun. I'm finding that the job is nothing to be intimidated by, just that you need the time, a warm dry space to work, and a source of good parts. This is a great father/son activity by the way, esepcially when you reset the valves. I am very open to corrections, criticisms, or more good ideas....I'm an electrical engineer by trade, certainly not an expert mechanic. My other generic suggestion is to not go cheap - its enough work that it should be done right the first time, and the difference in money saved is not worth the concerns later on, at least if your truck is remaining a member of your family. While doing mine, I keep reminding myself that, as the truck is used in parades honoring our vets, so is restoring the truck a way of paying tribute. OK, so on to the points, in no particular order. I will continue to add more as I finish the project. Good luck to you!!
- Make sure everything is CLEAN before reassembly. My machinist actually washes heads, sleeves, pistons etc in soap and water to lift out dirt.
- Keep careful track of all parts, using plastic margarine tubs, etc. Keep pistons and caps in order you take them out. If you choose to reuse rod bearings, they'd need to go exactly where they came from.
- Connecting rods and caps are actually machined together, and have matching numbers (1-6) stamped on them. To keep from spinning replacement bearings, it is essential to get them matched when putting them back together. Properly worn bearings will look like trout skin, all speckled - bad bearings will have concentric scrapes - if you can see copper in the scrape under the lead, then they're definitely shot.
I used a flat clean tabletop to carefully push the new bearing into the cap and connecting rod end.
- Some people advocate lightly sanding the crank bearing surface with emery cloth to seat the bearings. I would dissuade you from doing this - there's no way to get the grit out of the crank oil ports (crap would get pushed back onto bearing)
- Liberally prelubricate rod bearings and journal mains with "Lubriplate" and the cylinders with oil, to prevent dry cranking. Make sure the underside of the bearings are dry and clean.
- Plastigage is a nice product to measure the bearing size you need to use (if oversize bearings are needed) Essentially you smear the plastigate in, reassemble and torque the rod cap - then disassemble - the plastigage will retain its thickness, which can then be "miked."
- Head gaskets should ALWAY be put on dry - HiTech or HiTack can be sprayed on paper gaskets such as the head water jackets. Be sure to clean the waterjacket faces with emery cloth.
- While on heads, be sure to have the heads resurfaced and the valves reseated and valves ground. The Army uses a airtool called a featherduster to clean the head surface. This tool will "deplanarize" the head and cause premature headgasket failure. There is nothing like turning your heads over to a good machine shop - They took .003" off mine and it looks great. Money well spent as long as you don't ask my wife.
- The Multifuel uses a sleeved cylinder - rebuilding is a snap. The rebuild set includes a new piston, ringset, wristpin, and sleeve. Prices range from $100- $270 per hole (guess who's price $270 is !!!). Rings alone are about $25-$50 per hole, so in if there's any question, just swap the whole thing out. If you do hone and reuse cylinder and piston, be sure to at least change rings. If you hone, crosshatches must be at 60 deg angle to seat the rings.
- Sleeves often crack, up near the head surface. Check closely what you choose to reuse
- A wooden broom handle cut in half works great for pushing pistons out. If there is a ridge, you'll have to ream it off first...but if you are Removing and replacing the whole assembly, then just unbolt rod cap and push the whole thing out. The engine can be rebuilt this way right in the truck.
- The oil pan is a bear to get off. Take your time, and pry it off slowly by using the metal block near the front as a fulcrum. Clean the block and pan surface off (old gasket) thoroughly - I used a belt sander with light grit to get the old gasket off the PAN. Only scrape the block.
- Make sure all manifold faces and block head face are thoroughly clear.
- The M35 HEADGASKET has been updated MANY times - Make sure you get the right one. Many to most of the complete rebuild gasket sets do NOT have the most current headgasket. The one you want is one piece per head (no separeate rings) Its black neoprene with red bead sealer and metal rings BUILT in, not separate. Gasket set is still great to have for everything else - Gasket set is about $110 from George Manieri (Vt Commercial Salvage) and the best bet is Memphis for the correct head gasket ($75 each - do it right). Also the pistons for the naturally aspirated is different than that for the turbocharged deuce multifuel - look for the correct NSN for your truck
- Manifolds need to come off in the right order (you'll see what I mean) and must be torqued back on. I am intentionally not mentioning torque values because they varied on the LD, LDS, and LDT series
- The only touchy parts that have to get done right are seating the headgaskets, correctly torquing the head and rod bolts, and setting the valve lash. Take your time, remember the bolt order, and you'll be fine.
- For just doing lower block or head gasket, some people save time by removing the heads, intake and exhaust manifold, and turbocharger as one big assembly to save time. Don't do it - It may not allow the individual heads to reseat correctly.
- Scrape off all the carbon you find at the top of the sleeve if you don't replace the sleeve. Plug the oil galleries and coolant ports on top of the head so that junk doesn't get into the oil. Of course, use fresh fluids after all that work
- Put the truck in 4th set the brake, and then use a long screwdriver to turn the crank to the RIGHT ONLY when taking caps off or on, and resetting valves.
- My costs have been - $11.90 per bearing pair (Jerry Biro ,Hercules Parts), $110 for the gasket set (George, VCS), $150 for the new headgasket (MEMPHIS)$270 for the head work by Dale Spooner at Motion Machine in Williston, Vermont (there is no finer a machinist than Dale), $35 per hole for rings (MEMPHIS) OR about $600+shipping for sleeve/piston set (many vendors). You can find rebuilt engines or takeouts from $1800 to $3000, but then you don't know what you got. If you do it yourself then you will know exactly what you got, and for a lot cheaper.