Detroit 3-53

I have a Detroit 3-53 in a Dynahoe backhoe that seems to have a fuel problem. This machine sat for about 15 years, the old fuel has been drained and filled with new. I put new filters, new fuel lines and everything else in the fuel system is good and clean.
My problem is I'm getting air bubbles in the return line out of the head. I've checked from the pump to the tank and there are no leaks. From the pump to the secondary filter there are no air bubbles that can be seen in a clear hose.

I was convinced it was a bad injector(s) leaking compression back into the fuel. But I was told by a friend of a friend (an expert) that would be impossible because the injector pressure is higher than cylinder compression.

Now I'm kind of stumped where the air bubbles are coming from. It gets worse as the engine gets to operating temperature.

I posted this on the Heavy Equipment Forum and there is a link to it at the bottom. It's 124 replies long but is a good read.

It has a YouTube link of the problem I'm having in post 57, 77, 89, 112.

What seems odd is when I pinch the return line the bubbles go away as seen in post 89 and 112

The guys on the Heavy Equipment Forum are awesome and helped me out big time! I didn't realize I had a fuel problem but they spotted it right away.
They suggested to run the rack and replace the injectors. I totally agree and plan to do so come spring time.

I'm posting here to see if someone can tell me exactly what's going on with these bubbles. Why they go away when I pinch the hose. And if there is anything we might have missed.

Your help is greatly appreciated!
Blue

[/url]http://www.heavyequipmentforums.com/showthread.php?55607-Detroit-353

Does your exit fuel elbow have just a .60
or.90 hole in it. You should have 20 lbs
fuel pressure at idle. Need back pressure
on head.

The restrictor fitting was .080 but the book calls for .070. I put a .070 in and it doesn't make any difference.
I tried a .062 which made the spill test closer to the .6 GPM... No difference on the bubbles, actually made it worse.
The .070 is in now.

Not sure the pressure at idle.
I'm getting 70 PSI at 2650 RPM. The higher the RPM the more bubbles.

As I side note, it is totally possible to get compression leak back through an injector. I was working on a C15 Cat not so very long ago (14.7l
inline 6) that was a great cold starter but terrible hot. Those engines use mechanically actuated unit injectors (the difference is the are
electronically controlled via a solenoid so no rack). When it was hot I had air returning in the fuel from the head but none going in. Everything
else checked out okay. 6 reman injectors later and all was well. When hot the needle can become sticky and compression pressure gets forced
into the injector prior to it firing (which is when it gets pressurized) and voila you have air in the fuel. Good luck, Sam

blueboy,

I read through some of your thread on heavy equipment, didnt finish, it drifted quick lol.

I apologize if i say something you already know, im not trying to belittle or anything.

You stated you changed everything prior to running it after it sat for 15 years. Fuel lines & filters and now you have bubbles in your return side. So, i would start by checking all your filter gaskets, then resnug your line fittings. You didnt say if there was a check valve in the line or not.

If after that you still have bubbles in your return then from beginning to end, the fuel pump has a suction side and a discharge side. if you have bubbles in your return line, the only way i can think that would happen would be from the suction side. That being said, the supply side should have a check valve on it to keep the suction side full and not have to spend extra battery juice to spin it to refill the line. You more than likely wont see a leak on this side since it would be pulling air in, causing bubbles in your return, and when its off it would leak back to the lowest points collectively. All of my detroits have 2 filters and each set up a little differently, so if one of them is the highest point of your fuel system, i would look at it first it could be as simple as a bad gasket, loose pipe plug or fitting.

From the pump forward everything is under pressure, which would cause fuel blowing out and you would see bubbles somewhere else in the system. I would think if you have an injector problem you would see diesel in the oil since when not running, the fuel rail and bowls would leak at the crack and drain down. Since everything is under pressure from the pump forward my money would be on the suction side of the fuel system.

You said when you pinch down the return line the bubbles go away, i dont know how long you are pinching the line, but the only way to know for sure that you are eliminating the bubbles would be to pinch the line while in a bucket of diesel and let it run for at least 5 to 10 minutes, cause you could only be masking the problem, a little more backpressure would cause the line to pack the air a little more building up somewhere and then still coming out, just not venting to atmosphere as quick as your used to seeing. Just cause you dont see the bubbles for a second to two doesnt mean they have gone away.

If you think you have a fuel problem at the injector, get you a hammer and while its running with the valve cover off, take your hammer handle and push down on the injector and see if the motor runs any different. Since you have talked about pulling the injectors i am guessing you know how to set them afterwards so ill skip that. the rack doesnt contain any fuel, its only purpose is to allow more or less fuel, since its under pressure so i dont think that has anything to do with it.

Others are correct though, if your not making that detroit scream your doing something wrong, a screaming detroit is a happy detroit - haha

Sorry for the book i wrote, i just wanted to be complete in my thoughts and not offer a 1 line response. Keep in mind this is just my less than professional opinion. please let us know what you find so you can helps others out.

As previously stated there is either air seepage into the auction side of the fuel system. Or a worn injector .
Given the age and hours, the injectors owe you nothing. A fresh set of C45's are relatively inexpensive . The "c" injectors are a higher pressure and finer spray design for California emissions. The "c" units work better in every state than the horrible "S" injectors . The N injectors ain't bad but the C are better.

(quoted from post at 08:18:32 12/19/15)You stated you changed everything prior to running it after it sat for 15 years. Fuel lines & filters and now you have bubbles in your return side.

the supply side should have a check valve on it to keep the suction side full and not have to spend extra battery juice to spin it to refill the line.

You said when you pinch down the return line the bubbles go away, i dont know how long you are pinching the line,

Just cause you dont see the bubbles for a second to two doesnt mean they have gone away.

Since you have talked about pulling the injectors i am guessing you know how to set them afterwards so ill skip that.

Sorry for the book i wrote,

Click to expand...

I bought this machine in March, it sat that long before I got it.
The fuel problem is why I changed the filters and lines.

The parts manual shows a check valve by the tank BUT was removed before me. Starting never was an issue tho.

I pinched the hose for only a couple of seconds. I could try holding it for longer and see what happens.

Never did an injector change before but I know I need a tool to set the timing.


The YouTube link sows a clear line after the pump (pressure side) with no bubbles. Which should prove there is no air getting sucked in? The other line is the return when I pinch it and the bubbles go away.

https://www.youtube.com/watch?v=1s6QdjmQiOA&feature=youtu.be

I have a repair manual on the way, it should be able to tell me which ones are in there, but would it be a good idea to keep the same?

You dont really need a special tool to set the injectors. Its nothing more than a 1/4" steel rod machined down with a collar to act as a stand off that fits in the little hole drilled in the upper side of the injector. the length depends on what type of injector you have, but from everything i have seen, the length of it is not more than 1.058 inches. You measure from the bottom of the injector spring to the top of it. If you do an image search you will see what i am talking about. Pretty easy to make. do NOT go more than that 1.058" ish because it will open the injector more and the piston will hit the injector.

I wouldnt mess with the injectors until i knew that the suction side is not the cause of the bubbles.

If you pull the valve cover off there will be a something on the injector body telling you what style they are, and the color is important too, yellow, red, blue, 45, 35, C, N, S. they should all be the same, but it will still run even if they arent, just not as good.

I wouldnt mess with the injectors until i knew that the suction side is not the cause of the bubbles.

Click to expand...

id you check out the YouTube link above? Wouldn't that be convincing that there is no air in the fuel coming out the pump?

I saw the gauge for $25

In trying to clean out bio diesel from my 435, I put a sediment bowl with a shutoff and changed the fuel filter. I could not get it started later. The guy that fixed it found the sediment bowl restricted the fuel and the washer on the fuel filter was not copper and leaked. I thought I had blown the head gasket. Some times it is those simple things.

(repl
y to post at 11:38:41 12/19/15)

Click to expand...

Hello Blueboy,

Return line should have a restrictor fitting. It is screwed into the head. Manual wiil have the size. You Need to performe a spill fuel test. The manual again will have the proper amount and the rpm's to be checked at. Some engines have as much as .9 gallos returning to the tank. Air to the returne line usually means low fuel volume. You did not say if the engine is running O.K. If the fuel pump has low return volume, you may notice the lack of power at full engibe load,

Guido.

Hello Blueboy,

The reason I said you needed to check fuel spill back was to see if you had plenty of
volume. But if it shuts off at idle, the fuel pump is not providing enough fuel then at idle, you
myght as well replace the pump. You can get then cheap enough. Some time the seals go
bad in the pump and will suck air after the filters. I see were you changed the orifice.
Bet you the pump is the culprit! Thats my guess and i'm sticking to it!!

Guido.

Air to the returne line usually means low fuel volume. You did not say if the engine is running O.K. If the fuel pump has low return volume, you may notice the lack of power at full engine load

Click to expand...

But if it shuts off at idle, the fuel pump is not providing enough fuel then at idle,
Some time the seals go bad in the pump and will suck air after the filters.

Click to expand...

As far as I know there is plenty of volume.
The engine seams to run ok, but maybe not like is should under load.
The engine dies only if I idle down to fast.
The YouTube link 7 posts up should be convincing enough there is no air being sucked in.

Here is a spill test I did with different fittings. The book calls for a .070 fitting at .6 GPM
The original restrictor fitting was .080 and put out 1.090 GPM at 1500 RPM.
I put the .070 fitting in and it was .799 GPM at 1500 RPM.
I bought another fitting that is drilled out to .062 and it puts out .674 GPM at 1500 RPM
Not sure why the .070 doesn't match the GPM. But the .070 is in now.
The pump puts out 70 PSI at full speed.

(quoted from post at 08:54:04 12/22/15)

Air to the returne line usually means low fuel volume. You did not say if the engine is running O.K. If the fuel pump has low return volume, you may notice the lack of power at full engine load

Click to expand...

But if it shuts off at idle, the fuel pump is not providing enough fuel then at idle,
Some time the seals go bad in the pump and will suck air after the filters.

Click to expand...

As far as I know there is plenty of volume.
The engine seams to run ok, but maybe not like is should under load.
The engine dies only if I idle down to fast.

The YouTube link 7 posts up should be convincing enough there is no air being sucked in.

Here is a spill test I did with different fittings. The book calls for a .070 fitting at .6 GPM
The original restrictor fitting was .080 and put out 1.090 GPM at 1500 RPM.
I put the .070 fitting in and it was .799 GPM at 1500 RPM.
I bought another fitting that is drilled out to .062 and it puts out .674 GPM at 1500 RPM
Not sure why the .070 doesn't match the GPM. But the .070 is in now
The pump puts out 70 PSI at full speed.

Click to expand...

Hello blueboy

If you got air in the return line and you are positive it is not from the intake side of the pump, it has to be from pump seals sucking in air. Parked for many moons will dry them up. Snapping the throttle to idle makes the engine die means the buffer screw or the idle is not properly set. Loose fuel lines may be another reason for air, only the return lines though. Check the oil for dilution or diesel smell. You can plug the return line and see if you get power, it will do no harm. You can set the idle at a higher setting. The buffer screw should be adjusted with care. Idle RPM's shoukd not be raised more then 20. Be carefull doing that adjustment, it will take off for the moon if not done right.
Follow the manual exactly. It would be a good thing if you could get some help from a DD mechanic. A tune up would not be a bad idea. Then you would be able
to do it on your own if you need to in the future. I still think you nay have just a fuel pump that has dry seals,

Guido.

Blueboy,

did you get this resolved?

Hey tlock0331, no not yet. Been trying another trick but it hasn't worked yet. A guy suggested running Jet-A fuel threw it. Said it would clean the injectors. Actually the bubbles looked different, maybe less of them, maybe finer looking. It could be because it was clear instead of red. I ran the engine at 2000 RPM for 1 1/2 to 2 hours with the hoses in a bucket. The only diesel was from what was in the filters.
I do know that after the run when it was idling there were no bubbles. That is the first time this has happened.

I found a place I think will help, Leid Diesel Services in Newville, PA., about a 3 hour drive. I'm going to get some new injectors. Winter hasn't hit yet here in Pittsburgh, so if I can get them in now I should be ahead of the game. I'll give them a call Monday.

Merry Christmas everyone!

OK I give up! No more Jet-A fuel, I ran about 5 gallons threw it all together and it doesn't look like it's going to get any better. I hooked up the fuel lines and the bubbles look pretty much the same. Although, idling down does seems better.

I changed the oil yesterday. When I first got the machine I put in 15w-40 diesel oil before I knew better. Now it has Rotella T1 40w and a new filter. I would rather have Delo 100 40w but I have to order it. Next time.

I don't think this was mentioned before but I took some measurements on the exhaust manifold, at the #1 cylinder it is about 70 degrees colder than the other two.

On to the injectors!

Ordered injectors, feed lines, hight tool and gasket.
Let the real fun begin!

What's wrong with this picture?
I think I found my problem

Spring looks a little funny.

I found another problem, the exhaust valves are all over the place. It's a 4 valve head. Can't do No. 1 cylinder but the clearance on No. 2 cylinder front set is .027 rear set is 0.000 Zero! I can just barely move the little rocker that goes over the two valve stems. No. 3 cylinder front set is .016 rear set is .033

Two of the rocker shaft standoffs were on backwards and the valve spring was rubbing against it.

Who ever worked on this thing would be better off flipping burgers.

Bubbles! I still have bubbles! Acts like it did before. I don’t know what to think. I was sure I eliminated everything from the tank to the engine. I put a clear hose after the pump, I didn’t see any damn bubbles. The only thing left is the pump. I’ll double check the fittings but I think a new pump is in order. The hard part is done, it did need at least one injector and the valves set.

One thing about the bridge clearance on the rear set of valves #2 cylinder. I think that is what was making the engine loose power (post #1) and having a different sound towards the end of the haul up the hill. (post #7)
With zero clearance, when the valves get hot and expand they wouldn’t close and loose compression.

Compression is #1-325, #2-360, #3-310 That’s a cold engine and using the starter. The book says to run the engine at 600 RPM for each cylinder checked at operating temperature. REALLY?

After I put the new injectors in I checked the valve clearance on #1 cylinder (which I didn’t do before) and they were both .020. So front to back was .020, .020 .027, zero, .016 and .033

To add to my problems, getting a decent manual has been difficult, but that’s the way it is in my world. The one from Yesterdays Tractor was good but out dated (returned). I ordered one from a dealer and is was one thick 1 1/2” book with glued solid binding that looked like a cheep reprint with faded pages. (returned!!). Ordered this one from eBay, an original manual copyright 1990 material (Revised / Updated from the original issue dated February 1985 edition). Publication Number: 6SE202 Printed in the U.S.A. http://www.ebay.com/itm/201384227834?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT I haven’t gotten it yet but I think it’s a keeper. The price went up $30 after I got mine.

The valves are set to .026 and the injectors are set to 1.496. I readjusted the fuel rod and the control levers, their set even on all the injectors. So far I haven’t messed with the governor.

Apparently there are no bubbles, it was/is fuel agitation.

I talked to Ervin at Leid Diesel, he said that's what it looked like (Emailed the video). Also to hold the hose end below the surface of the fuel in a bucket to be sure. Last time I did that was with the bad injector and there was definitely bubbles.

After checking the fuel the engine was at running temp, I checked the valves and the gap was .027-.028, .001-.002 bigger from being set cold. The injector was 1.497, .001 over the cold setting. That was on the #1 cylinder, I didn’t see any need to go further or to make any adjustments. And I noticed the compression was much higher when I was turning the engine by hand. When I set everything cold it was a lot easer to turn. Which means the overall compression should be higher. Also the exhaust manifold temperature on each cylinder is within 5* of each other. Wonder how this machine goes in the snow…

Thanks everyone for your help,
Blueboy