4-71 detroit info/help

[willie59]

The more I read on that site and the links (
http://www.tejascoach.com/ddcoil.html) the sicker I got about running 15/40 all the years in mine. It is a yard machine and not tons of hours but still make me :Banghead:Banghead

Yep, there's been a lot of research done on those engines, and Tejas has tons of experience with them in their fleets. These are old engines. A good many folks who happen to have one today just don't know the quirks these engines had. And they're so old, the info is not out there in the mainstream of engine maintainence. It's all tier III and regeneration now days. With the old Detroit; it was fuel, oil, and stand on it.

 

[TSK415]

Thanks for all the info and help. Well the update, after talking to the local diesel shop while looking for an exhaust manifold, he asked me about the fuel. I was always under the impression that diesel lasted forever. So I drained the tank and got about 15 gals. of what looked like tranny fluid. Put 10 gal. new back in with some cetain boost /injector cleaner. The engine got hot in about 15 min. and to 180 in about 30 min.

Hmm, still not certain what your describing your wet stacking condition. Just to be sure we're on the same page, you can see three hex fittings just behind the oil filter can. The one nearest rear of block is a 90 degree flare fitting, that's what's called the "air box drain". There should be a short piece of tubing connected to that fitting to extend the drain to just below oil pan to keep drippings from getting on the block and oil pan. There will be a crankcase vent pipe as well, usually located at rear of engine, and will be about a 1" diameter pipe. Are you getting leakage from the air box drain or the crankcase vent?

the air box drain is good and clean lots of air. Crankcase vent, nothing like you described, just the line off the govenor is that it?

Engine temp; when you were aiming a temp gun at it, were you checking the temp of the block? The engine block on a Detroit doesn't get terribly hot because there is air from the blower moving all through it feeding the cylinders. This also keeps the block cool. The only part that has coolant in it is the engine head. And Detroits used a low volume water pump. You should see some movement of coolant in the radiator neck when thermostat opens,but your not necessarily going to see a rush of coolant, maybe just movement of coolant.

At the head,exhaust, radiator, hoses, oil cooler. No movement at the radiator, now I get a rush of coolant when the thermostat opens. The temp guage is off.

Also, since you don't know the history of the engine, it's possible someone has been using multigrade 15W/40 in it, they will slobber when you use that oil. I would advise, now that you've changed it to SAE straight weight oil

Yep it had 15-40 in it, I put 30wt in and will go to 40wt

Can you pull the exhaust manifold to see which cylinder it is coming from. It could be a stuck injector too. I know the n65's are pretty notorious for that.

I pulled the homemade elbow off the manifold and all the runners looked the same just a lot of carbon/ soot build up.

I dont think the governor has an issue, unless someone messed with it and even then it wouldnt cause wet stacking

As stated I would pull the injectors and have them tested
You really need to have someone re-install them that knows what they are doing and has the correct timing tool.

Is this a 2 valve or 4 valve head, if its a 2 valve, it never will run real clean

I did'nt want to mess with the governer just check the settings, my gm book has the flow chart for tuning the engine and one of the steps to get to the rack adjustment is the governer. I want get it to the point of running the dog snot out of it before I pull the injectors Yep it's a 2 valve

ATCO, help me a bit here, does this look like the correct governor cover on top? This is a shutoff lever and I was thinking the top just had a one shaft coming out of it, also what is this spring doing, thats hooked to it? It cant go in the forward direction, because it will hit the extra shaft and so if you pull the stop lever back to stop it, the spring doesnt do anything.
Maybe the lever goes forward over the front shaft, but I always thought I had to pull back on it

Do I see oil residue below the bellhousing? Wonder if the rear seal is leaking?



These questions, has nothing to do with possible wet stacking, just wondered about these things

How should the governer be hooked up? the light spring isn't hooked up to anything so I have to kill it by hand. The front seal is is wet, I think you are right about the rear seal.

I would ad that the inside of the blower looks normal and the outside of the engine also looks normal

Never looked in a DD blower before now I know


Thanks again for all the help

 

[willie59]

ahh, now I see, look at that nasty exhaust pipe. :tong

Got your temp up there now, fresh fuel, some SAE 40...start her up and run her like your mad at it. BTW, nice looking old crane :yup

 

[~0le]

71-series... Great engines. The Detroit 2-stroke temp gauge measures the temperature of the coolant just after it comes past the thermostat. The perferred temp gauge uses a capilary tube with a sensing bulb. These bulbs come in various lengths. Get the correct length so that the tip of the bulb extends slightly into the coolant stream. Having a stationary engine in your dragline means you can mount the gauge where convenient and observe it at your leisure. (Most of my experience is with 6-71 powered on-highway coaches from the 1950s). We had a cap-tube temp gauge in the engine compartment to use to calibrate the electric gauge that was forward on the dash.

Unlike 4-strokes, the 2-stroke Detroits can't tolerate temps of much over 200 degrees. Even with a 15 pound cap on the radiator, the head(s) are prone to cracking above this relatively low temperature. Remember, these engines were designed in the 1930s. The alarm stat/shut-down system is always stamped to activate at 203 degrees or 204 degrees or 205 degrees. This is the sequence of operation of the engine's temperature control equipment as things warm up: Thermostat opens. Shutters open. Fan clutch engauges. Every engine has a thermostat, the other two (extra cost options) were specified only if the original purchaser was more concerned about fuel economy and life cycle costs than about initial purchase cost. There are two common thermostats: Nominal 170 degrees and Nominal 180 degrees. Each starts to open at its rating and is fully open by 15 degrees warmer. The 170 (fully open by about 185) is used when there are shutters (the shutter stat opens the radiator shutters somewhere between 185 and 190), and a clutched fan (the fan clutch stat is set to activate between 190 and 195). The 180 (fully open by approximately 195) is used when there is no additional temperature control equipment. In both cases, all the cooling equipment (if properly functioning) is fully functional by 195.

Wet stacking occurs only when both the incorrect oil AND long periods of idling are perpertrated upon the poor engine. Run the correct oil, minimize idling, and you won't have any problems with wet stacking. Wet stacking is marked by oil seemingly POURING out of every pore of the engine and exhaust system. Some excess smoke comes out the exhaust, but not much compared with what is STREAMING out of the lowest clamped joint in the exhaust pipe. We used to tell the drivers, "Don't idle the engine any longer than a traffic signal," and "upon start-up, just build air and go." The instruction, 'run the engine hard for an hour' is necessary only to clear things up after changing the oil and changing the operating parameter.

I'd be a little concerned about the oil on the blower lobes as indicated in your photo. Every blower horn I've pulled off has exposed lobes that were clean as a whistle. The concern is that when sufficient oil leaks into the air intake, the engine can run on its own (the mechanic runs away, the engine over-speeds to self-destruction). The Detroit Diesel book indicates that you need two special (matched) pullers to disassemble the blower. One turns left, and one turns right. When I was working on these engines, we sent the blowers out for rebuild, but I've been told that one can pull the drive gears off the ends of the lobe shafts with two pullers that turn the same direction, it just takes some finesse. (I've had a Detroit 8V71 run away on me when I was driving a 10-wheeler dump truck. It was in gear and loaded to gross. The engine noise changed. That was all. It was always under control. Later that day when we were messing with it trying to diagnose, it took off again. THANK GOD my associate (the truck's owner) was standing there at ready with a wire tied to the shut-off lever on the governor. Valves were floating in the 3/4 second or so that it took him to realize it was time to pull that wire. It turned out that there was a rough spot on the control tube of the rack (spring-loaded fingers...supposed to prevent this sort of thing). I.e., it was fuel control under the valve cover -related. My concern with your engine is that it appears to be 'oil in the intake' -related and pulling the fuel cut-off lever won't help. Make sure your emergency shut-down (cuts air) works. It would be a real shame to lose that engine....or worse, injure yourself or someone else. Don't freak out over this, but they don't call it 'run away' for nothing.

Good lookin' crane, man. Hang in there with it.

~0le

 

[TSK415]

Thanks again for the info and help. The emergency shut down works You would think for as many 4-71s out there, it would be pretty easy to find an exhaust manifold :beatsme

 

[Willis Bushogin]

471

Thanks again for the info and help. The emergency shut down works You would think for as many 4-71s out there, it would be pretty easy to find an exhaust manifold :beatsme

I have a exhaust manifold, I bought to go on a 4-71 in a Drott I was working on and the man never paid me, so I didnt install it. I dont know about the freight, but I paid $100 for it and thats what I want for it plus the freight. I will package it up free. If you want it PM me and let me know