Detroit 4-53 hard to start

[Not You]

Wasn't sure where to post this, so I started here. I have a trencher with a Detroit 4-53 engine. It starts really hard after it's been sitting overnight, even in warm temperatures. It blows a lot of white smoke and I have to crank up the throttle and hold the key on even after it starts to fire or it will die.

It will fire pretty quickly when you first try it, but it will die if you let off the key. After you get it started and running, it starts and runs fine after being shut off.

My thought is the fuel is bleeding back to the tank after it sits. There is an inline electric fuel pump that was put on between the tank and the 1st fuel filter to address this problem. The pump is working fine. I even tried letting the pump run for about 30 sec. before starting it and that helps, but doesn't solve the problem.

There don't appear to be any check valves in the system.

I let it sit overnight and took off both fuel filters. The 1st filter (suction side) was about 80% full of fuel and the 2nd filter (pressure side) was about 50% full of fuel.

What else should I be looking for?

 

[willie59]

Every two stroke Detroit I've ever worked on was fitted with a low cracking pressure check valve at the inlet of the primary filter. If yours doesn't have one, install one. I have a local hyd hose/fitting shop that has a good supply of various sizes of low cracking pressure check valves, should be pretty easy for you to source if you have a good local shop. Additionally, and not related to your problem, if you're using 15W/40 multigrade oil in the engine, please stop doing that, those engines don't like that oil. You need to use an SAE40 oil with 1.0% sulfated ash oil less, less is better. Delo 100 SAE40 meets the specs the best, Delo 400 does not, and there are others out there that meets that spec, just getting hard to find them.

 

[Not You]

Thanks for the info. What is considered low cracking pressure, 0.8 bar? I've found the online for cheap.

I was thinking of putting a check valve as close to the tank as possible to keep all the fuel upstream of that point. You would put it right at the primary filter?

Also, I am using straight 40W oil. You're right, it's hard to find.

 

[lantraxco]

Detroits usually have a gear type fuel pump and while your electric pump may push fuel, I doubt it can push fuel through the gear pump. It sounds like there's somewhere that air can get into the system and yet not let fuel leak out, weird but not uncommon. If the tank is lower than the engine, the return line from the head back to the tank will pull a vacuum from gravity and if there's anyplace air can get in, the weight of the fuel running down to the tank will suck the air in. The elbow coming out of the head where the return line attaches should have a restriction in it to create fuel pressure in the fuel rail for the injectors also. As Willie sez, there's usually a check valve at the inlet to the primary filter, especially if the filter is below the fuel pump.

 

[willie59]

I can't recall exactly what cracking pressure the proper Detroit check valve is, I just know I've worked on plenty that have that check valve fitted to the inlet of the primary filter. Like Lanway stated, make sure the fuel lines are good, leave no chance for air to suck into the system, and yes, as he stated, the brass fitting in the head that the return line hooks to should be a restrictor fitting.

 

[wornout wrench]

If you are getting lots of white smoke on start up, you are getting fuel. The smoke is unburnt fuel.
Chances are that there are some broken piston rings. The engine can not make enough heat on the compression stroke to ignite the fuel.

Is this a new problem, or has it been coming on for some time.
Do you know the history of the machine
Has somebody been using either on it.

One of my favorite tricks to start an old screaming jimmy that is showing her age is to pull the shut down and run the engine over for several second (10 seconds or so) then move the shut down back to the run position. This will get some heat in the cylinders and then the fuel will ignite better. Might take a few tries. One of the advantages of this is that you are not flooding the cylinder with unburnt fuel and not washing the sides of the cylinder and pistons.
If you have a good set of batteries this works real good and no either involved.

If you have an electric shut down, you need to manually overide the shutdown to keep it in the no fuel position.

Hope this helps

 

[Not You]

I know this problem has been occurring for a while, the previous owner put the electric fuel pump on when they couldn't get it to start after they changed the fuel filters. There's no manual pump that I can see. The machine has less than 500 hrs on it, so it sat a long time at some point, but has been used a fair bit in the last year. I'm hoping the engine itself doesn't have problems with that low of hours, but sitting unused at some point for years probably didn't help anything. I do not believe they used ether and I haven't/won't.

I'll check the return line coming out of the head. It looks like it's just a 90 and the manual doesn't say anything about a restrictor fitting. The fuel tank is at the bottom of the machine, so it may be getting air in that return line.

 

[kshansen]

I'll check the return line coming out of the head. It looks like it's just a 90 and the manual doesn't say anything about a restrictor fitting. The fuel tank is at the bottom of the machine, so it may be getting air in that return line.

The fitting out of the head should have some numbers stamped on it if it is a restriction fitting. They look just like normal fittings but inside they are restricted, forget what size different engines used different sizes. OK did a quick look in a couple parts books and looks like .080 is the most common size for the 71 series, don't have book on 53. This should be stamped on the fitting, might have to clean off paint but usually easy to read.

But like wornout wrench says if you have lots of white smoke you are getting fuel and the most likely problem is low compression.

I'd be pulling airbox covers off the side and looking through the ports at the rings and poking them to see if they spring back nice, and looking through the ports at the cylinder walls to see signs of wear. Just got thinking, are there covers on the 53 series? Or will you have to pull the blower? Only worked on 3 or 4 53's in the last 45 years and the last one was a couple years back.

 

[Shimmy1]

Just another thought, even though the hour meter shows what it shows, there is no guarantee that it is accurate. If you could find an old school Detroit guy, I would think about doing an overhead. You could probably do the valves, but the injectors are a bit of an art.

 

[Not You]

I'm hoping the hours are correct, but you're right, you never know what is actual. I'm no mechanic by any means. I'll pull that return fitting off to see if it has any markings on it.

 

[Randy88]

Those vintage trenchers had steel welded tanks on them with steel pipe lines inside them. I'd isolate the entire fuel system, bypass the suction line and return line, install some rubber hose's and put a check valve in the fuel line where you shove the hose's into the fill hole of the tank, start it up and run it, shut it off and let it sit overnight, this will eliminate the fuel tank and lines for issues, and with a simple check valve installed on the line, you should eliminate the entire fuel system for issues.

If its sat for any length of time, the tank will rust at the top and when got back using it, the rust will work loose and suck up into the line and lodge under the check valve seat, I'd also put an inline cheap fuel filter between the tank and the check valve to see if it gets plugged with junk.

I just torched apart a steel tank off my trencher, the steel fuel pipe was cracked, not bad enough to cause issues when running but enough to leak fuel and get a slug of air in the line upon start up or shortly after causing the engine to die, I don't think that's you issue, but I do think you have junk in the tank and its plugging any check valve you may fin idn the system, allowing fuel to flow back in the tank and suck fuel out of the filter housing depending on where its located.

 

[Not You]

Those vintage trenchers had steel welded tanks on them with steel pipe lines inside them.

What are you calling vintage?? It's younger than me! Haha. Here are a few pics of what it looks like. It has an inline filter below the electric pump, maybe I need to replace that while I'm at it.

First pic is the inline filter and inline electric pump at the primary fuel filter (oil filter is to the left). Second pic is the return side of the fuel coming out of the head (The 90 appears to be a restrictor fitting - it says R70 on it). Third pic is the secondary fuel filter and you can barely see the inlet side of the fuel line going into the head. It's behind the 2 red and 1 yellow wire bundle.

 

[wornout wrench]

I know this problem has been occurring for a while, the previous owner put the electric fuel pump on when they couldn't get it to start after they changed the fuel filters. There's no manual pump that I can see. The machine has less than 500 hrs on it, so it sat a long time at some point, but has been used a fair bit in the last year. I'm hoping the engine itself doesn't have problems with that low of hours, but sitting unused at some point for years probably didn't help anything. I do not believe they used ether and I haven't/won't.

I'll check the return line coming out of the head. It looks like it's just a 90 and the manual doesn't say anything about a restrictor fitting. The fuel tank is at the bottom of the machine, so it may be getting air in that return line.

Classic senario of when either gets used.

Engine will not start
Get the either
Hey, it started
Give it another shot, and another, and another...
you get the picture. I have seen it too many times.

Fuel plumbing on a jimmy should be from the tank to the primary filter, primary to fuel pump, fuel pump to seconday filter, secondary filter to head, return line to tank with the orifice fitting in the head.
Follow your fuel lines and you should find the fuel pump. It should look something like this

http://dieselpro.com/detroit-diesel-fuel-pumps.html

(I just used that link for the pictures, no idea who they are)

 

[Not You]

Fuel plumbing on a jimmy should be from the tank to the primary filter, primary to fuel pump, fuel pump to seconday filter, secondary filter to head, return line to tank with the orifice fitting in the head.
Follow your fuel lines and you should find the fuel pump.)

Yep, that's how it's plumbed.

 

[kshansen]

I see in the last picture that there is what looks like a block heater cord hanging on the fuel line to the filter. One thing that might tell you something is if you are some place you can plug this in and warm up the engine before trying to start in the morning. If it does then fire right up with little cranking it would tell me that compression is the main problem.

I know form past experience that a detroit with almost no rings left on the pistons will, once forced to start and warmed up a bit will run much better than you might expect. Wish I had taken pictures many years ago of the pistons out of a 12V-71 we rebuilt, almost every compression ring was broken, grooves about twice new width and this was in a truck that was being used daily in a gravel bed. Did need a sniff of either even on 80º days to start but once up to speed burned nice and clean for an old two valve head engine. It did strat a bit better with new pistons and liners along with many other new parts!

 

[Not You]

I see in the last picture that there is what looks like a block heater cord hanging on the fuel line to the filter. One thing that might tell you something is if you are some place you can plug this in and warm up the engine before trying to start in the morning. If it does then fire right up with little cranking it would tell me that compression is the main problem.

Good idea. I can plug it in and try that. I'm starting to think it needs an overhaul which is not an option at this point.

Another thought - the battery is fairly weak, would replacing it help get the engine to crank faster and move the fuel better or does that not really have anything to do with it?

 

[wornout wrench]

Good idea. I can plug it in and try that. I'm starting to think it needs an overhaul which is not an option at this point.

Another thought - the battery is fairly weak, would replacing it help get the engine to crank faster and move the fuel better or does that not really have anything to do with it?

Is it turning over slowly or is your battery not lasting and you need to jump it to get it to start.
If it is just tuning over slowly, but it does start, it is probaly not your battery but another problem like dirty terminals or a bad conection somewhere causing a voltage drop and dragging your starter down. Or, it could be a bad starter too. But the faster you can get it spining for start up the better.

I would go with kshansen's idea and plug in to see what is happening.

As far as either goes, it is not a bad thing if used the proper way. Too many times i have seen a guy dump 1/2 a can of either into the air cleaner and hit start. Argh!!!!
Since Cat went to direct injection, and how long ago was that, they have start aid on the machines. It is either but delivered in a small metered dose right into the manifold. The small little poof gets the engine to light with out causing the damage that a huge dose does.

If your machine is still running and doing the job you need, and the dollars are not there to rebuild, installing a either start system could be an idea.

Those old jimmy's were tough old engines, they will run with multiple broken rings and still do okay. Depending on how much you use it, you could go years before you need a rebuild

 

[Former Wrench]

Chech the valve lash. Sounds like they are out of adjustment

 

[Not You]

Is it turning over slowly or is your battery not lasting and you need to jump it to get it to start?

It turns over slowly, but it always starts and doesn't need a jump.

 

[wornout wrench]

Chech the valve lash. Sounds like they are out of adjustment

Agreed, a tune up would be in order, if nothing else other than to see if it is all within spec.