Bench testing 4-108m

[Dirk Williams]

No joy. Motors turning well Now, great oil pressure, I've got a dribble of diesel fuel at the injector bleed ports, but not solid. I've got intake water cycling, and in/out, and I've got white smoke from the exhaust.

Still won't fire.

Question should I have a flow from the return fuel line, from on top of the injectors, where a hard line runs around the back of the motor, to the top of the fuel filter.

While priming the motor today I had diesel pissing out the seep tube. Now that the motors turning over " battery cranking" I'm not getting any return pressure pushed, fuel returning in that time.

If I had a good "air free" fuel loop, wouldn't I be seeing excess fuel returning to the tank, OR is the 4-108 capable of using all fuel to the injectors.

Guys I know it's something simple.

I suspect I'm not bleeding the fuel,system enough.

Any thoughts. Back at it again in the morning.

Thanks again for,your input.

Dirk

[Warby12]

I usually end up bleeding our 4108 with the starter motor after doing as much as possible with the hand prime. Bleed on top of the fine filter, side or top of the injection pump then injectors.

We have a lot of fuel return when running, never checked it while bleeding.

[bletso]

There is also a bleed screw on the injector pump.

[Cheechako]

My 4-108 wanted to run so bad I couldn't bleed it without it firing. I never bled anywhere but at the injectors. But then I never had the injector pump off, only the head.
What was discovered about your starter? Sounds like it's working now.

[leftbrainstuff]

Shutoff the fuel. That's how all diesels are shutdown.

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[leftbrainstuff]

Originally Posted by Dirk Williams

No joy. Motors turning well Now, great oil pressure, I've got a dribble of diesel fuel at the injector bleed ports, but not solid. I've got intake water cycling, and in/out, and I've got white smoke from the exhaust.

Still won't fire.

Question should I have a flow from the return fuel line, from on top of the injectors, where a hard line runs around the back of the motor, to the top of the fuel filter.

While priming the motor today I had diesel pissing out the seep tube. Now that the motors turning over " battery cranking" I'm not getting any return pressure pushed, fuel returning in that time.

If I had a good "air free" fuel loop, wouldn't I be seeing excess fuel returning to the tank, OR is the 4-108 capable of using all fuel to the injectors.

Guys I know it's something simple.

I suspect I'm not bleeding the fuel,system enough.

Any thoughts. Back at it again in the morning.

Thanks again for,your input.

Dirk

We bleed our 4-236 first at the injection pump then at the injectors.

Usually I only need to bleed number one before she starts.

I purge the rest of the system with our electric pump through the fuel return.

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[Dirk Williams]

Thank you left brain. I've been researching for a couple hours now. Has anyone ever actually timed their diesel pump. I had two lines actually scribe marks. One on the engine front housing and one on the actual pump. I lined these two lines as that's the way the diesel pump was when I pulled it off the motor.

I know the pumps working as I've got water thru the sea water pump exit or exhaust side. If the diesel pump wasn't spinning the saltwater jabsco pump wouldn't turn? Right.

Dirk

[Dirk Williams]

Li,e I've said, I ain't a mechanic. I took the starter back down to the rebuild place, he clamps it down puts the two cables to it and the starter ran as it should. Had him draw me a diagram of the circuit, actually two posts.

When I was booking it up, I noted that one post had a red felt under it, and the second on the back of the starter had a black velvet. I simply applied power to positive, and ground to the black side.

Was backwards. Womt make that mistake again, I wrote in heavy black pen pos/neg.

When I returned to the shop we hit the starter with power, boom worked as advertised.

As I seated the starter motor the bottom mounting hole stripped the course threads . I've never had course threads strip inside like this before.

Sooooo I had to drill it, and set a helicoil. Actually my friend did that while I fitted a fuel return line to the motor.

As I was leaving I noticed a small leak on a female fitting directly into the pump itself. It's possible that air is entering their. I'll replace the rubber in the morning and reseat the fitting, may have to reprime as well.

I had truly wanted to learn this motor, I'm taking a clobbering via this learning curve.

Dirk

[a64pilot]

Originally Posted by Dirk Williams

Anybody got some cool old 70/75 motocross bikes?



Dirk

Years ago I felt sorry for my cousin and gave him my 73 WR 250 Husky, I still regret that.

[Dirk Williams]

Never owned the WR, I've had several 74.5 250 Mags, the Reed valves models. If it's a husky it's cool. At one time I owned 56 Husqvarna's 10/15 years ago people just gave me their old junk bikes. I lovingly rebuilt them piece by piece. Raced them traded them, and sold them.

Just one of my other hobbies. I've got 15/ 18 rebuilt bikes in my shed. I've been on a CZ kick the past year, got a couple 1971 250 yellow tankers. A 1971 380 yellow tanker and two 1973 380s all runners.

Got enough parts for at least a couple more complete CZ"'s.

Got a 1971 250 Maico, and 1971 400 Maico, and a 1969 360 Maico. A 1969 Yamaha DT-1 a 1970 Yamaha 360 RTI. Got a Cheney DT-1 Yamaha 1968. Enough for,one more.

Got a couple American Eagles a 1968/69 238 Kawasaki version and a 1968 360 oval case husky version.

Couple1976 KX Kawasaki's, and several vintage trials bikes.i just like classic iron. Like my HR33 the older stuff appeals to me.

We still race these bikes with an orginization called AHRMA, it's a hoot, racing these things.

In fact we often have some of the older motocross legends show up. They might be 70ish, but man are they fast on these old bikes.

Dirk

[GILow]

Originally Posted by Dirk Williams

Thank you left brain. I've been researching for a couple hours now. Has anyone ever actually timed their diesel pump. I had two lines actually scribe marks. One on the engine front housing and one on the actual pump. I lined these two lines as that's the way the diesel pump was when I pulled it off the motor. N

I know the pumps working as I've got water thru the sea water pump exit or exhaust side. If the diesel pump wasn't spinning the saltwater jabsco pump wouldn't turn? Right.

Dirk

A few alarm bells ringing from this post.

1. Injector timing is absolutely critical. There should be a procedure in the workshop manual for setting the timing. If it was disturbed during the rebuild (likely) then a set of marks that may have been accurate before the rebuild should no longer be trusted.

2. You are cranking the engine with the raw water feed connected and open? Very risky, depending on the exhaust setup. There is a very real risk of flooding that lovely rebuilt engine with salt water. When doing this sort of work I get the engine going properly BEFORE supplying raw water. Let the engine run for maybe ten seconds at most, then turn on the raw water supply.

Finally, I don't know anything about your particular engine but I would be hugely surprised if the functionality of the raw water pump was in any way an indication of the state of the diesel pump.

[Dirk Williams]

The raw water system is actually a large bucket with fresh water

please correct me if I'm wrong. The jabsco pump is turned off the cam, via a gear on the front of the motor. As the jabsco spins via the gear on from, it also engages the diesel pump, gear which is indexed.

Their is a set of scribbled limes , one on the side on the engine case. This is a machined timing mark from the factory. Their is also a machine scribed line on the diesel pump. My understanding is that this is the initial timing lines, and critical to be spot on alignment wise.

This pump was rebuilt at the diesel pump shop here in town, almost 700.00. Was told they had set the timing and that the # 1 piston needed to be Tdc when the pump was placed back on the engine.

And I agree with your last part. Other then The cam driving the main gear, which drives the jabsco pump gear, which is connected to the diesel,pump. Don't see how that has anything to do with timing.

This motors out and on the bench.

I'm not understanding your saltwater in the engine statement. I did dip the oil as I was concerned about the new oil filter cavity not filling. It did and I topped the oil off with zero signs of water.

I'm still confused as water in the cases was the reason for this rebuild. How would the salt water get into the cases via the exhaust.

Educate me.

Dirk

[Celestialsailor]

Originally Posted by Dirk Williams

Li,e I've said, I ain't a mechanic..

Dirk

Then perhaps it is time to consult one. A great book is Calders "Mechanical and Electrical Manual. It will be an enormous help.

[GILow]

Hi Dirk,

Water gets back into the engine from some exhaust designs where the force of the exhaust gases are required to push the water from the muffler to the outlet on the boat. In these designs it is possible to flood the exhaust pipe while trying(and failing) to start the engine as the absence of successful combustion means there is no method of driving the water out of the exhaust.

I did not realise the engine was still on the work bench. In that case I am not sure I would have bothered with connecting any kind of cooling flow, if the intention is merely to see if the engine will start. It all gets too complicated from my experience. Usually with a bench engine I would ignore/disconnect every auxiliary device and just turn it over till I got combustion, then immediately shut it down.

I hear what you are saying about the pump timing but I personally would not trust that the timing is correct. In theory it will be but knowing how to set the timing is one of the useful skills you might want to obtain and doing the job eliminates one more variable when trouble shooting. Of course some injector pumps need some slightly specialised tools to set the timing (mine needs a dial gauge for instance) and the cost of these tools might make the job a lower priority in the trouble shooting process, but I would still consider the timing suspect even if the engine did start.

But I do OCD better than most people. :^)

Matt

[Dirk Williams]

No arguments. I've got a great mechanic, we're building the motor in his shop. He's a very skilled diesel mech, just not a 100 year old motor. I'll look the books you suggested on Amazon and order.

I'm actually making progress every day. I'm only working 4/6 hours a day on this thing. I don't know how to quit. I will figure it out. I saved thousands doing it myself, being retired my times cheap.

Patience will win the day.

Thanks for the book tip.

DW