4-71 detroit problems

[kvadder]

I recently purchaced a bantam excavator w/ a 4-71 detroit. It had no radiator cap when I got it, so I filled the radiator to about 3" below the top and put a new cap on it 7#. At start up it pushes about 3 gal out the top of the radiator. The thermostat is good. I checked the flow on the radiator, and it seems to be clear w/ no restrictions. The water pump is pumping the correct direction. It runs about 180 deg. when operating, and runs great. It almost apears that the radiator is aquiring exhaust or blower pressure. It even overflows the radiator when just cranking, and I just don't think that I could get that kind of exhaust buildup w/o the engine running.

 

[dieselpaul]

wow--my first gut feeling would be fire ring or injector tube, sealing off when temp expands. other thing that comes to mind is by-pass system--misplumbed-stopped up

 

[dieselpaul]

meant to include cracked head--

 

[Walt Davies]

Head gasket comes to mind.
Walt

 

[HeyPigFarmer]

Head gasket, cracked head, cracked block - gotta remember with a Detroit the whole thing is pressurized.

 

[guido]

Hello KVADDER.
You can also try to retorque the head. There bolts are 5/8 11 and get torqued 175 to 185 Lb.
May be that will help temporarly. Sounds like compression is getting into the cooling system real bad!.
Like the other post mentioned , a head gasket or cracked head is more likely the problem.
Guido.

 

[buickanddeere]

More of a fire ring than a head gasket.
If the head is off this is the time to install some C60, C65 or C70 injectors.
Much superior spray pattern to the old S series injectors. Sleeve/piston kits are dirt cheap. If the head is off then may as well do an inframe.
Once again the old low compression S series pistons have been updated with N series. Cold/cool weather starting is much improved.
With the C injectors and N pistons. It will make less smoke and burn less fuel to make the same HP.
Don't grind the valves or seats. It sinks them and lowers the compression. Even with the N pistons it still needs all the compression it can get.
New valve seat for certain.
There are updated valve springs and cam follower springs. They are stronger and less likely to break. More that one DD has clattered to a halt after whacking a valve into a piston.

 

[trucker40]

Cracked head,should be easy to find if its getting that much pressure in the radiator.

 

[guido]

Hey BUICKANDDEERE.
The fire ring comes with the head set, so it is part of the head gasket.
By the way if you get a recon head, you should reset the injectors cups.There was a bulletin to that effect and I did it every time a replaced the heads.You are wright abount the N pistons, the N pistons 18.7 to 1 compression ratio made for better starting, and better performace all the way around.
Guido.

 

[dieselpaul]

the ''fire ring'' IS the head gsk. that is to say that it is the only thing that seals cyl to head.--one per cyl. the rest is rubber---paul

 

[buickanddeere]

It's not the usual type of head gasket so that's why it's more of a fire ring leak. If it isn't a cracked head form running low on coolant then somebody dumping in cold water.

 

[k_vadder]

Thanks to all! Your imput is gratly appriciated!