Detroit Series 60

[njdevi11]

My Fire Department has a 1995 seagrave with a detroit series 60. Recently its been surging when pumping. This happens usually only when the transmission is in drive. When driving we usually keep it out of D (its an auto 4 speed in case that wasn't clear).

Idling and high idle is fine. I think this kinda sounds like my 6.2 and the cold advance circuit being energized while the engine is warm. Is it a possibility that this is a timing problem? I know the engine has been looked at by a few techs and they cant figure it out. Some are calling it a transmission problem.

JUST FYI: A fire engine's drive train goes from engine->trans->pump->axle.

You pump in drive, the pump is kinda like a transfer case, when the pump is engaged the rear axle output is in neutral. I don't know what kind of trans it is, My guess is most likely an Allison thats mechanically controlled. I could look it up if anybody wants to know.

Any body got any ideas?

[3bals]

It could be an issue with the relief valve on the pump sticking or not holding properly? Is it a manual relief valve or an electronic pressure/RPM limiting device?

Jody

[njdevi11]

Thats a good point, I haven't thought of that.

The relief is a mechanical valve and the throttle is mechanical as well. We are having some issues with the relief valve no functioning properly, its less of a pressure relief and just a valve, you crank it down till it opens and then it wont close till you crank it up even as the pressure drops.

Usually we'll just keep it closed, and even when the engine is surging ive never noticed water spilling out the relief. Aside from that, it will surge in drive while its in motion on the road as well.

[962500]

Sounds like your fuel pressure is low. it should be in the 60-80 psi range when the engine is running at high idle. i have heard of another series 60 with the same problem and it turned out it was the injector cup was cracked. but we had to pull the cylinder head and send it out to get tested to find that out. does it only do it when it is in a certain gear on the transmission or when ever the engine is under heavy load? what tests have been done to the engine already? more info would help.

[njdevi11]

I'm not to familier with the big detroits, are the series 60 engines direct or indirect injection, is the injector cup your talking about like the prechamber on the 6.5's? Is this 80lbs pressure from the lift pump? Will lift pump pressure and return line restriction affect timing like the 6.5 pump?

Usually the surging is when the engine has a moderate load on it, when pumping or driving, usually the surging only happens when the transmission is in drive.

Ill try to gather some more information, the guys in the white hats at the FD don't like me knowing more about anything then they do and are not going to help me solve the problem so any information i get is going to be hard to come by.

[962500]

The Detroit's series 60 is electronic unit injection. It is direct injection, the injector cup is what separates the injector from the coolant in the cylinder head. it is often pressed into the cylinder head and coolant and fuel flows around it to cool and feed the injector. The lift pump is bolted to the back of the air compressor and runs off the engine. could be something as simple as fuel filters need changed though. Does it have its normal amount of power? have you had it in to a Detroit dealer to get the injectors checked? they can check them by just plugging it in to there computer.

[jam93]

I have one of these in my 97 freightliner 500 det and it has and is still doing the up and down up and down noise and what we have found is that it can be a cracked injector tip, crack on the side of the injector in that cup housing also the fuel lines could be sucking air somewhere the fuel filter base could be cracked or not a true 12v going to the side of the computer that controls the fuel because two of the batt is for the computer bad bank in the computer and in our case our motor would loose prime and that was caused by a crack in the side of the injector on the body that goes down in the head.also could be bad fuel those are just some of the thing that could be wrong but still these are very good motors mine has 1.8 million miles on it 6.5 to 7.0 mpg not to bad i think..:)