Ethanol warning, barn finds and where has all the rubber gone in this installment of ‘Tech Tips’
Something not right with your historic military vehicle? Steve Turchet answers your questions on how to keep ’em movin’!
ETHANOL WARNING?
Q: I have heard a lot about ethanol in gasoline. My question is, will it cause trouble in 6-cylinder flathead Dodge engines from WWII? —B. Morgan
A: There is a lot of misinformation about gasoline and what’s been/being done to it. Based on my experience and also many things I have read on the subject, the usual mix of 10 to 15 percent ethanol added to much of today’s gasoline will not harm the engines of WWII or early M-series HMVs, which were, after all, designed to run on the lower octane and often poor-quality fuels of their times. However, most of today’s gasoline will damage vintage rubber, such as NOS fuel pump diaphragms and some carburetor gaskets and seals, so these items should be updated. Likewise, since today’s gasoline does not contain lead, it’s smart to install hardened valves and valve seats when rebuilding vintage engines. I have also noticed that today’s gas seems to remove paint quite well — especially when paint removal isn’t desired.
BARN FIND
Q: Your column is the first thing that I read in the magazine and have picked up many useful tips. I learned a few tips from this particular tip that will help me in the future. But I wondered why you did not advise Randy (and others) to drop the oil pan and give it a good cleaning. It would also be an excellent time to eyeball other potential problems, metal particles in the pan, loose bearing caps, fried rod bearings, etc. It is also a good time to check and clean the oil strainer. After the M37 sat for 20 years, it a safe bet that there would be a lot of nasty, coagulated stuff in the pan. In many of the old engines that I have worked on that have sat for years, I have had to clean out the oil pans with putty knives just to get the bulk of the crud out to get the pan ready for the solvent tub. It unusual not to see metal and other engine parts in the bottom of the pan, i.e. valve keepers, nuts, washers, cotter pins, etc. and oil strainers that are completely plugged with goo. So my motto has always been, drop the pan before you try to fire the engine. Just wanted to share my thoughts with you; I enjoy and admire your work. —Jerry Bubolz, M37Grunt
A: Thank you for your letter, Jerry, and of course you’re right, there are a lot of things to do before trying to start an engine that’s been sitting for 20 years — even if it wasn’t seized up — and I wrote an article about it which I believe is available on the magazine website: “Waking Up HMV Zombies.” However, I only have two pages at most for Tech Tips and I’m often left with a choice of whether to print several letters and give a few tips on each, or to print only one letter and use two pages responding in detail. In Randy’s case, I felt the first thing to do — and the first thing I would do — would be to try to get the engine unstuck. Once unstuck, one would proceed with other things, as you mentioned. I’ve had good luck using the brake fluid and the “tap and wait” method to free up frozen engines. It has worked in cases I never thought it would, including on an IHC Green. Diamond engine, and a Hercules L-head engine, both with cast-iron pistons that were so badly rusted into their cylinders it was hard to believe they would ever move again. After a week, however, I had both engines running. I’ve found ordinary brake fluid works better than Liquid Wrench, WD-40, or any other commercial preparation I’ve ever used. I first got the idea in my teens when I noticed, on an old truck I had, that wherever there was a brake fluid leak there was no rust.
BARN FIND - FOLLOW-UP
Q: I realized after I sent you the email that you could print pages and pages on how to restart an old engine. But, you have limitations. Your article was succinct and very helpful. Keep those good tips coming. The brake fluid idea is invaluable. —Jerry Bubolz, M37 Grunt
A: Thanks, Jerry!
WHERE HAS ALL THE RUBBER GONE?
Q: I am new to the hobby of military vehicles. I bought a stock 1966 M37 about 3 months ago. The military tires were brand new then. I drive the M37 to work every day, which is about 15 miles. I also use the truck on weekends for off-roading and camping, These are not long trips, but my new tires seem to have lost 50 percent of their tread already! Were they just cheap tires and should I look for better quality replacements?
A: All tires sold in the U.S. (and most countries) have to meet certain government specifications as to the quality of the materials, weight loads ratings, pressures, etc. Still, there are “cheap tires” that may wear more rapidly than more expensive brands; but, unfortunately, rapid wear is the worst trait of U.S. military non-directional tires. When I worked for a construction company in central California, I drove a 1964 Toyota Landcruiser FJ-40 on which I had installed brand new 9.00 x 16 military non-directionals. Even though this truck weighed half of what an M37 weighs, these tires wore out at a shocking rate. I could see noticeable wear after only a hundred miles. If stock military appearance is not a factor, I suggest replacing the non-directionals on your M37 with tires of a different tread design.
HOT HUBS
Q: I have a Pinzgauer 710 I use for a daily driver. I have noticed the gear-reduction hubs get hot when driving on the road at high speeds. Should I be worried?
A: One of the disadvantages of gear-reduction hubs on “portal axles” as used on Unimogs, Pinzgauers and HMMWVs is that they generate a lot of friction and therefore tend to heat up at high speeds. Gear-reduction hubs are the main reason why vehicles so-equipped usually have lower top speeds than vehicles with conventional axles. Besides keeping your Pinz’s top speed under the recommended limit, I advise using the best gear oil you can find (usually synthetic) and/or a top-quality gear oil additive, and changing it often. Even expensive oil and additives are a lot cheaper in the long run than having to rebuild your hubs.
AIN’T NO SUCH ANIMAL?
Q: I had an idea about replacing the 6-volt generator on my ex-Navy CJ3B with an alternator for more efficient battery charging but I was laughed out of an auto parts store when I asked about a 6-volt alternator. The guy said there ain’t no such animal!
A: I’d say it was time to find another auto parts store. There are indeed 6-volt alternators available from a variety of sources. Do a web search.
BRING BACK THE GLOW
A common problem for early model HMMWVs was that they wouldn’t start in cold temperatures. At first it was thought that the glow plugs were at fault, because they seemed to be burning out at a rapid rate. In fact, it was reported that the U.S. military was replacing HMMWV glow plugs at an average rate of one every three minutes! However, the problem turned out to be caused by the glow plug control units, which were also burning out. The solution was to replace the early style mechanical controllers with sold-state units.
Send your favorite Tech Tip or question to Steve Turchet at military@aimmedia.com
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