Detroit 4-53N higher idle when warm

[boomerang]

Admittedly ,I haven't delved into the issue much at all other than to make sure the fuel linkage was returning to the idle position every time, but after a cold start, both engines idle at the same RPM. After the port engine has been run for a while and comes up to operating temperature, the idle is 2-300 RPM's higher. I get a little uncomfortable when shifting at the higher RPM's because ,although probably more than adequate, the wheels are heavy 26" diameter ones and the shafts are only 1-1/2" and to my mind, there's a lot of inertia to overcome.
This engine does have over 5k hours on it and the other only 1200 but they both run so darn well I'm fully ready to roll up my sleeves and start educating myself on Detroits.
I realize these engines are dinosaurs so I hoping I can coax some of the old Detroit paleontologists out and offer some advice or ideas.
Just to be clear, when I say old, I mean experienced...Lepke

 

[tiltrider1]

We haven’t heard much from Lepke lately, which does concern me. Hopefully, he just hasn’t seen anything worth commenting on and not a health issue.

 

[CharlieO.]

We haven’t heard much from Lepke lately, which does concern me. Hopefully, he just hasn’t seen anything worth commenting on and not a health issue.

He commented some earlier this week.

 

[boomerang]

Whilst perusing the Hatteras owners forum I came across a post with the exact engine and symptoms I'm experiencing. I guess I'll need to try to find an injector timing gauge gizmo and a couple of other assorted specialized Detroit tools if I want to be able to work on and repair my own stuff. Thankfully, I have all of the service manuals. Oh well, the good news is at least the engines are owner serviceable. There's a lot to be said for that feature in this day of computerized and specialized technician-repair only mechanical stuff in today's world.

 

[Lepke]

Something is out of adjustment or worn. Have the rocker arms been adjusted lately? As the lifter, linkage, rocker, and injector top wear, it changes injector timing. Valve/injector clearances change from cold to hot. I know there are videos on Youtube on setting the rack, installing injectors, or adjusting the governor. You have the service manual so I won't try to write it here,
With the videos and a service manual it should be no problem to check mechanical settings.
Ebay is a good place to find used Detroit tools
A couple places on line for a timing tool:

Kent Moore J1853 Injector Timing Tool For Detroit Diesel | DP J1853 | Diesel Pro Power

# 1 source for Detroit Diesel injector timing tool J1853. Worldwide shipping direct to you. All parts for Detroit Diesel ship within 24hrs of order confirmation.

dieselpro.com

Kent-Moore J-1242 Detroit Diesel Injector Timing Gauge -1.484"

Used for checking and setting the injector timing on various Detroit Diesel engines, specifically the Two Cycle 53, Two Cycle 71, and Two Cycle 92 models

tillmantools.com

 

[boomerang]

Something is out of adjustment or worn. Have the rocker arms been adjusted lately? As the lifter, linkage, rocker, and injector top wear, it changes injector timing. Valve/injector clearances change from cold to hot. I know there are videos on Youtube on setting the rack, installing injectors, or adjusting the governor. You have the service manual so I won't try to write it here,
With the videos and a service manual it should be no problem to check mechanical settings.
Ebay is a good place to find used Detroit tools
A couple places on line for a timing tool:

Kent Moore J1853 Injector Timing Tool For Detroit Diesel | DP J1853 | Diesel Pro Power

# 1 source for Detroit Diesel injector timing tool J1853. Worldwide shipping direct to you. All parts for Detroit Diesel ship within 24hrs of order confirmation.

dieselpro.com

Kent-Moore J-1242 Detroit Diesel Injector Timing Gauge -1.484"

Used for checking and setting the injector timing on various Detroit Diesel engines, specifically the Two Cycle 53, Two Cycle 71, and Two Cycle 92 models

tillmantools.com

Thank you for the link to the tools and the explanation of what's causing my issue. I'm a bit apprehensive to start the project because I'm not real familiar with working on these engines. Our previous boats, with their Perkins and Lehman diesels, weren't as intimidating to work on because on the outside, they looked just like any other simple simple gasoline powered 4-stroke engine that I am used to working on; a circulating water pump on the front of the block, a cam lobe-driven mechanical fuel pump on the side etc. These 2-stroke Detroits with their blower boxes ,gear pump fuel pumps and circulating pumps bolted on the side appear foreign to someone who hasn't worked on one much (I had a Chesapeake deadrise with a 6-53 but it had been freshly rebuilt and other than oil and filter changes, I never had to do as much as tighten a screw on it).
Thanks again for taking the time to help and it's good to see a familiar face...well, avatar...make an appearance on here again.

 

[Lepke]

If you have a temperature reading gun, read the ports where they come out of the head when the engine is running. It will show you if the cylinders are producing equal power. Read the ports of the other engine, too.
If they're very different it can point to other problems.