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detroit 3-53 nock in lower end untill oil pressure comes up and idel running high


Hi all
new to the board, first time posting I have a friend that just picked up a franklin skidder that has a DD 3-53 in it, it runs real good but at start up it has a rap till the oil pressure comes up.
I advised him to drop the pan and roll in new bearing,who knows old they are, it's a cheep fix. what is stumping me is the idle on it, when it is cold it idles high, as she warms up it comes down but it takes a while for it to do that. he has adj. the screw on the side of the gov. to idle it down but as she warms up she stalls out.
Is it normal for Detroits to do this when they are cold.
I have a manual for a 3-73 that shows the adjustment for the Governor, is it the same as a 3-53 or different?


The screw on the side of the governor is NOT the idle adjustment screw. That is the buffer screw on your engine. On a 53, a properly set buffer screw is one which you set while the engine is running. While running, back it out until the engine runs real rough. Slowly turn it clockwise until the engine evens out. If you have a tach, adjust until the buffer increases engine rpm 25rpm or so. When this happens, back off the buffer adjustment one quarter turn counterclockwise.

To adjust the idle rpm, you need to remove a small cover on the rear of the governor. This cover is above the flywheel housing. When you remove the two 7/16" head screws you simply need two open end wrenches to change the idle speed. Usually a 7/16 and a 1/2" open end wrench. You loosen the locknut and turn clockwise to increase engine rpm. Usually the governor has a working range of 500-800rpm in industrial type applications, and a 400-600rpm idle range for automotive applications. On my automotive 53's they seem to like 550-575rpm idle speed.

The way that the oil pump works on a 53 is that it is a gear drive constant volume pump in relation to engine speed. A cold engine when started should have 50psi of oil pressure for at least 5 minutes before the engine is warmed up. When the engine is warm, idle oil pressure will be about 7-10psi and the governed oil pressure will be around 30psi. If you are not getting any oil pressure when cold, check your gauge, and then the bypass spring on the side of the oil pump. Your gauge may be reading wrong, or the bypass spring will be gummy and letting the oil pressure dump right back into the pan. If you still have no oil pressure after checking with a good gauge, I would not run the engine any more. You must have a spun bearing somewhere, or a loose cam bearing.

If it is really cold outside, and the injectors are a little gummy from sitting the engine may fire on just 2 cylinders for maybe 20 seconds before the third kicks in. You will know when a Detroit is not running on all cylinders. Idle and running speed will be rough. When the rack and injectors are properly set the engine will sing through all running speeds. They are very smooth running engines.

I unfortunately do not know of any Detroit shops in Rhode Island, but I primarily purchase all of my parts from Leid Diesel in Newville, Pennsylvania. Timothy and the bunch really know their stuff. They have been messing with Detroits for a few generations now. I am down on Long Island, and have 53 series manuals and a bunch of Detroit specific tools. I have rebuilt my 4-53T and 6V53T engines. I would be glad to send you scans from the 53 series manual. I just have to get it out of my truck.


Butch B

be very careful as to what you are adjusting, if you are adjusting the buffer screw it is VERY possible that the unit can run away and distroy its self and you may not be able to shut it down. The buffer is adjusted after the engine is warmed up and the idle is set you then adjust the buffer by screwing it in very slow until the RPM starts to elevate then back it off slightly and burp the throttle open and back to an idle the engine should come back to idle or just below idle and bounce back to idle speed. as for oil pressure detroits warm and at idle have extremely low oil pressure but if it is knocking something is very wrong checking the rod and mains or replaceing them is a good idea.

Norm W

A Detroit, once it is running, only uses the top half of the bearings on the connecting rods. If the bearings are worn they will knock till the oil pressure comes up. At idle the pressure would be low due to the excess clearance. These engine will keep running under very adverse conditions. Their main enemies are dirt and lugging. They are happy running flat out.


Make sure it has the right oil-has to be STRAIGHT 40w CH-4.

My 2-71 knocks pretty hard when it first starts running, but it's some kind of combustion knock.


I'm sorry or the long wait on the thank you reply ,life got hectic and I forgot that I even posted this
but I do thank all for giving me all the info and taking the time to do it
that 53 is still running the owner is going to be using it to move some logs around with the skider it is in. still knocking and still going strong