I have a Komatsu 75 S-3 crawler and I have a question about the use of the compression release particularly when the motors cold. I have the owners manual and they don't even make reference to it. So am I suppose to engage the comp. release until it starts or just until it starts to turn over then release it? Tell you the truth I can't tell any difference in the way the motor turns over whether your using it or not. Looking at my parts manual it shows the comp. release as a long tube that goes the length of the motor right below the head on the left side ,doesn't look like there's much to go wrong with it . So if anyone can help me out here I sure would appreciate it, thanks. Mark
With good batteries and a good starter there should be a noticeable difference in how easy and how fast it will spin over with it released. The old rule of thumb was open release, spin motor until you see oil pressure, then close release while it was turning over. Once she busts off release starter button or key. I like the old ways....
Thanks for the reply Junkyard. That's what I did the other day it got down to about 25 degrees overnight and I suppose it was about 30 when I tried to start it. I held the comp. release in until she was turning over then released it being she wasn't plugged in it was a little slow to start but eventually did. It has some abortion on it they call a glow plug there's only one and it has a hand pump you use to pump some fuel into the intake after you have the glow plug heated up so I guess its supposed to be like a torpedo heater I guess but it doesn't work so its something that I'll have to fix because I don't want to use starting fluid on it. Thanks again Junkyard. Mark
Mark, Not finding a lot of info on the "Glow Plug" thing but this page might give you something to start from:
Did a little more looking and found an old Shop manual, they sure did not spend too much effort on the system as this is all that is in the book!
I have often wondered if there is a modern manifold heater that could be installed in something like this. Either mount a grid heater of some kind where the air comes in, or drill and tap several places in the manifold for plug type ones. With modern batteries I assume it would be no problem to do this electrically but physical parts would be the challenge.
You know, it's funny you say that. Looking at the 250 in my A-car I pondered modifying the grid setup from a 5.9 or something. Possibly a couple of them. A little machine work and you'd have some adapters for mounting. Hmmmm might have a little cottage industry here! Haha
The 8.3 Cummins also used them. Might be a way to get bigger ones. And maybe leave them on for 2 minutes or more. I know a few smaller engines that use them, but it would mean like 6 heater plugs in the manifold to get the same number of heater plugs per cubic inch of displacement.
It sure would be nice on cold days. When those old motors finally bust off it sounds like somebody is in there with a hammer pecking away! I'm going to look closer at mine and take some measurements. I don't have an 8.3 grid to measure but I've got a 5.9 laying there.
I was also going to say, you would want to hillbilly it in there first to make sure it will even make any difference before cutting up the air inlet system. Or maybe just use a hair dryer or heat gun (or a couple) as proof-of-concept on that particular engine if it is too difficult to make a trial run of the grid heater.
I know a bit of heat on the intake manifold of an engine can do wonders for starting when cold. Had to get an older Mack started one day years ago on a cold morning. Batteries were not super good and I did not have any go juice in a can. This truck was carrying a asphalt spreader. Truck driver said "Would a bit of heat from a large propane torch help?" Seems the spreader had one of the Weed Burner on it that they used to clean off cold asphalt. https://www.harborfreight.com/propane-torch-91033.html Lit that sucker up and carefully warmed up the intake without starting the truck on fire, got in and hit the starter and it fired up like the middle of August!
Thank you very much for that file Kshansen it was very helpful. You should read the Komatsu owners manual if you want to have a confusing read. Who ever translated from Japanese to English didn't have a a very good grasp of the English language not to mention knowing the machine itself. The service manual and parts manual leaves a lot to be desired also. I have to reinstall the fuel line that comes from the float tank ( where the hand pump picks up the diesel ) to the hand pump and back to the intake I haven't a clue why anyone would want to disconnect it. This machine originally came from the east coast and it doesn't even have a block heater on it. My old 72 Mack didn't like it when it got down around below freezing if she wasn't plugged in but my 94 Mack with the electronic motor starts fine if I forgot to plug her it in. Thank you all for contributing I appreciate it you have been very helpful. Mark
I'm not familiar w/ this system AT ALL but I see where it says, clean screen & spray hole..?? Is there fuel being introduced along w/ heat from the glow plug? IF So.. google "thermostart".. its what ford uses on there tractors.. A screw in glow plug, fed by fuel from an overflow can, off the inj. pump return fuel. It'll start a tractor in a second.. screws into the intake.. Just a thought.
I have read that heat guns or a hair dryer works pretty good probably be a lot simpler just to use one of these if it wasn't for the fact I would have to drag the extension cord out every time because sooner or later you might find yourself somewhere where you don't have any juice. Mark
That's how this system works it has one glow plug in the intake manifold and it has a hand pump on the dash, when you pump the fuel in it atomizes the fuel and the glow plug ignites it just like a torpedo heater. Mark
By the hair dryer I just mean proof of concept. Get out there on the coldest morning and see if it does the trick. Then you know an intake heater will probably also work. If it is still balky then you might look for other solutions.
Massey used a similar setup on the little Perkins motors too. Nothin like a controlled burn in the intake!
compression release must have been an option my 75S-3 doesnt have one.
Yup, thermo-start plug heater for the Ford & Perkins.. I haven't run into one on the Yanmars, but its talked about on the net a lot. I guess the thread size will be the determining factor.??
Damned Allis farm tractors with the 3500 engine had intake glow heaters, almost useless as to making heat in a cold intake. Do great at killing a battery! In 1975 I watched a IDIOT, trying to start a 1960's cold soaked Freightliner then relegated to yard work with a six bolt head 190 Cummins, was a new yard man and had no clue what he was doing had been below ZERO for three days highs of low teens daytime. Went out, ether'd the intake stack really heavy(oil bath behind front tire), jumped in the seat and ARUMP, click click click. Sat for a second then pulled compression release would barely turn so got our yard hotstart cart and proceeded to charge batteries. Five minutes later MORE ether, like half a can, ARUMP, click click click. So the saga continued until he finally got called away for a few minutes more, came back EMPTIED a can of ether in the stack this time, we were ALL in the shop watching the moron by this time. Got in the seat, hit the starter and it lit up, INSTANTLY, then sucked ALL the ether laying in that air cleaner, over-revved, shot the center head(we suspected at least two head bolts were broken and at least two/three others cracked) into the bottom of the doghouse. Engine was junk when we finally got to looking at it later, poor guy was sitting in the cab eyes as big as dinner plates after the BOOM!!, crapped himself, got out of the truck and quit.
We used to call that pre-heater set up a fire breathing dragon. You pumped up the fuel pressure to it and hit the glow plug button and it started a fire in the intake manifold. They work real well if you keep them up. The glow plug takes a lot less amps to heat than the grid heaters use. The old 155 Komatsu dozers needed to use that thing when ever the temperature got below 50 degrees F. The engines lasted forever until you got operators that didn't know about using the heater. They would use liquid cocaine and then the engines went down hill.