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power unit problems of the detroit variety

Started by Bert, October 24, 2013, 08:15:11 AM

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Bert

Hi Guys,

Need some Detroit diesel advice. My mill is powered by 671 that's ran trouble free for the past 16 yrs. A few days ago the sawdust blower plugged up while sawing and I idled it down to clean out the bark. When I went back to sawing (throttled up) it started blowing what looked like smoke (heavy white) out the breather. Could be steam but not sure. No water in oil though. The next day I started it up cold and sawed abt 3 logs with no problems and then it started doing it again. I guess something is opening up once it warms up. Any ideas? I don't think its blowby from rings since it starts easy and doesn't do it until it warms up. Lack of water in oil kinda rules out O-rings in the head. Maybe a cracked liner or head?
Saw you tomorrow!

NMFP

Check head gasket and head.  Had a similar issue with a rock crusher a few years ago, not as severe though and turned out to be a cracked head.

Are you noticing any coolant levels decreasing?  How about your temperature gauge?  Is it higher than it was a few months ago?

Keep us informed.  Easy fix though if its head or gasket.

Good luck!

Bert

These detroits don't really have " head gaskets" just a series of O-rings, fire rings, and an oil seal. I think if an o-ring went it would fill the oil pan up with water. I've kinda ruled that out. Cracked head i'd guess would do abt the same? Wish I could give some decent info on coolant level but my rad cap is shot and it kinda looses some water around it while it runs anyhow so no real way to monitor that. I've been trying to find a new cap for abt 2 yrs now. Temp seems normal. I'm a little bit hesitant to run it to try doing any more diagnosing. Once it heats up and starts pouring smoke out the breather, it misses a little. Runs fine cold.
Saw you tomorrow!

giant splinter

White smoke can be fuel that not igniting, did the (smoke) cloud dissipate or not, did the cloud smell like diesel or was there no smell?, did you smell any motor oil smell at all and was the smoke white or slightly blueish white,   from your description it indicated that it could be the same smoke you see when you fire it up on a cold morning ...... in that case if its going away in a couple minuets the chances are its the fairly normal signs of Detroit in need of servicing, try giving us more information and a better description of what appears to you to be .... is it steam or smoke? If you are letting it idle for extended periods of time its best to shut it down rather than letting it load up.
My experience is not with 671 but I have a 453T and a standard 453 and although similar your 671 has different habits, lets hope one of the 671 guys chimes in with some true 671 advice.
The Detroit diesels in the 53, 71 and 92 series don't like to be left running at an idle and the smaller models like 453, 353 and 671 can load up in a short time ...... the instant you ask them to go back to work the throw out all the loaded up fuel that it was not able to burn and may run rough while doing it, this occurs in mostly non-turbcharged models. My 453  1978 series in a 1964 deuce and a half water truck could choke itself on raw fuel buy running at idle for an extended period of time, The 453T in a Frick 00 seemed not to be so fussy about idling in between logs.
roll with it

Bert

I cant definitively tell if its smoke or steam. It seems to dissipate pretty fast, but then again the fan and such is right there blowing it around. Kinda smells like oil, but not like oil burning if that makes sense? No smoke out the exhaust just the breather. We don't idle it excessively. I idled it down for maybe 3-4 minutes just to get the bark away from the blower intake.
Saw you tomorrow!

giant splinter

Bert,
Are you running a thermostat and are you not finding any signs of water in your oil, have you tried sticking your finger in the oil filler inlet and wiping the underside of the rocker cover to see if you have any water/oil crud building up on the inside of to cover? this stuff is a grey looking sludge that can build up on the underside of cover lid and the cap.
I did not have an intercooler or oil cooler on my 453, the 453 T had the coolers, what specific model you have as there are many configurations and some are equipped with extra cooling gear ( more ways for water and oil to get mixed or just disappear) do you know the model designation and horsepower rating of your 671?.
I can ask my mechanic later today to see what he thinks it may be.
roll with it

Bert

Yes on the thermostat. It runs abt 180 degrees or up to 195 on a hot day in some nasty logs. I have not found traces of water in the oil. There is a little slime on the oil filler and rocker cover but nothing major.
Saw you tomorrow!

giant splinter

I just heard from him and he should be back later this afternoon, He asked about your last service and if your air cleaner and crankcase ventilation systems are free of anything that could restrict them. He should be back before 5 or 6 at the latest he says thats pacific daylite time.
roll with it

Bert

Nope no restrictions on the intake side. The only cranckcase ventilation I know of is the breather tube itself. That is what is putting out all the smoke. Not sure of HP rating. I had the starter rebuilt last yr and it was made in 1945 so this is an older 671. Naturally aspirated.
Saw you tomorrow!

mmartone

Fuel and air filters in good shape/recent? White is unburned/raw fuel, different than rich/black exhaust. Do you know how to short an injector to stop if from firing, done with the valve cover off. Thats how to determine which cylinder it is. Seems strange it only does it when its warmed up, could be an injector. As long as the coolant level is up, its not a head o-ring or cracked head or otherwise.
Remember, I only know what you guys teach me. Lt40 Manual 22hp KAwaSaki, Husky3120 60", 56" Panther CSM, 372xp, 345xp, Stihl 041, 031, blue homelite, poulans, 340

Bert

How would unburned fuel get in the crankcase? The exhaust does not smoke. Its the breather/ blowby tube that's pouring out the smoke.
Saw you tomorrow!

circlesawn

Removed my post thinking the white smoke came out the exhaust.

circlesawn

Smoke out the breather is a whole different issue.

Bert

 Experience is what you need right before you get it.
Saw you tomorrow!

nk14zp

Quote from: Bert on October 24, 2013, 11:02:44 AM
These detroits don't really have " head gaskets" just a series of O-rings, fire rings, and an oil seal. I think if an o-ring went it would fill the oil pan up with water. I've kinda ruled that out. Cracked head i'd guess would do abt the same? Wish I could give some decent info on coolant level but my rad cap is shot and it kinda looses some water around it while it runs anyhow so no real way to monitor that. I've been trying to find a new cap for abt 2 yrs now. Temp seems normal. I'm a little bit hesitant to run it to try doing any more diagnosing. Once it heats up and starts pouring smoke out the breather, it misses a little. Runs fine cold.
Before 1959 the 6-71 had a headgasket.
Belsaw 36/18 duplex mill.
Belsaw 802 edger.
http://belsawsawmills.freeforums.org/

Beaudeane

My series 60 Detroit had similar issue with fuel getting in water. Injector tubes fixed problem 3 years ago
Don't think of it as `gun control', think of it as `victim disarmament"

Bert

Quote from: Beaudeane on October 24, 2013, 02:39:50 PM
My series 60 Detroit had similar issue with fuel getting in water. Injector tubes fixed problem 3 years ago

Was the smoke from the breather or exhaust? Fuel was getting into the water?
Saw you tomorrow!

loggah

The early two valve engines did have a head gasket, i would guess its leaking by .
Interests: Lombard Log Haulers,Tucker Sno-Cats, Circular Sawmills, Shingle Mills, Maple Syrup Making, Early Construction Equipment, Logging Memorabilia, and Antique Firearms

giant splinter

Bert,
Check your engine for fuel dilution, you may have one of the internal fuel supply lines leaking diesel internally ..... if it is mixing in with the oil it can cause a catastrophic failure in a short time. check the oil and smell it ..... if its thinning out or smells like diesel fuel, check to see if the oil level is climbing on the dipstick , check the internal lines for pin holes or cracks.
roll with it

bandmiller2

Bert,mayby the old girl is flat $ss wore out, and its blow by.All the old two valve head detroits were smokers.If you could find a decent four valve head Detroit your clutch should fit and fuel economy jump.Diesels have come a long way in the last 60 yrs. Frank C.
A man armed with common sense is packing a big piece

Bert

ok so... apparently the starter is older than the motor itself. Its a 4 valve head. I've pulled the head and am taking to a shop to have it pressure tested. I'll post the results.

Saw you tomorrow!

bandmiller2

If its a four valve head Bert its worth fixing , sorry to malign your old buddy. Frank C.
A man armed with common sense is packing a big piece

Bert

Thanks words of encouragement bandmiller. She is an old buddy, so I hate seeing her in intensive care. I cant even begin to quantify the lumber this old Detroit has sawn. Shes on the truck and we'll send her off the shop in the morning. Detroit man seems to think its something in the head.
Saw you tomorrow!

Bert

And the final diagnosis is in.... We laid the old girl to rest yesterday. After much testing, finally found a crack in the block between the airbox and end cylinder closest to the radiator. This was allowing a small escape of antifreeze as well as air pressure from the roots blower into the crankcase. Next step is to find a replacement.
Saw you tomorrow!

nk14zp

Belsaw 36/18 duplex mill.
Belsaw 802 edger.
http://belsawsawmills.freeforums.org/

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