Old Detroit 671 Ti

[krattski]

Hey all, I have a 46 Ocean Sportfish that has been on blocks for 7 years. Ready to put back in the water (Lake Superior, always been in fresh water).
Any tips for restarting the 671's after long slumber?
Thanks in advance.

[Woodland Hills]

New oil and filters, clean fresh fuel and filters, check impellers. Verify that flappers will work in case of oil or fuel leak causing a runaway then crank over with the shutdown button depressed until you have oil pressure. Then start them and check that you have water coming out of exhaust. Have someone in engine room to watch for leaks.

[skipperpete]

Originally Posted by krattski

Hey all, I have a 46 Ocean Sportfish that has been on blocks for 7 years. Ready to put back in the water (Lake Superior, always been in fresh water).

Any tips for restarting the 671's after long slumber?

Thanks in advance.

If your engines have a heat exchanger cooling system and use Jabsco pumps you should take off the cover plates and inspect the impellers, after 7 years of layup it’s reasonable to assume they need replacing. Pro marine engineers often manually rotate engines that have been standing unused for lengthy periods ( more than 3 months) because humidity corrosion can damage liners and pistons.
If you have turbo’s, take off the air filter and see if the compressor wheel can be easily rotated.
Check the alternator belts.
Take off the valve covers and move the fuel rack rods manually, they get sticky if left unused
It’s a huge advantage to have had your boat in fresh water but 7 years laid up is too long to just climb aboard and pull the trigger, she needs some TLC first because a lot of damage can occur very quickly if the startup is not properly prepared for.
Pete

[GordMay]

Greetings and welcome aboard the CF, krattski.


Detroit Diesel 671
Manual ➥ https://www.jensales.com/content/ppp...-in-line71.pdf
Parts ➥ https://cg83527.org/images/pdf/dd671manual.pdf
Troubleshooting etc ➥ https://dieselpro.com/detroit-diesel...ural-4lve.html

[Cadence]

Originally Posted by krattski

Hey all, I have a 46 Ocean Sportfish that has been on blocks for 7 years. Ready to put back in the water (Lake Superior, always been in fresh water).
Any tips for restarting the 671's after long slumber?
Thanks in advance.

I might pull the valve covers and lube the cam pull the injectors and put in some lite oil and let it sit. discount anyone that mentions WD40 or either.

[FAST FRED]

The big fear is stuck injectors . You must pull the valve covers and watch that all the injectors slide together , even one stuck can cause very high RPM with no control.

Engines converted from bus or OTR trucks sometimes have a lap to cover the intake , shutting down the engine , but if its spinning fast the gaskets are usually sucked out of the blower , and it has to be rebuilt. Far less time & effort just to take a look.

Sometimes a stuck injector can be freed by spraying the shaft with PB blaster or similar and moving the injector link.

Do not remove an injector as a special measuring tool/pin is required to reinstall the unit, and its best to watch it being done before attempting it.

If injector can not be freed they can easily be rebuilt. Used to be about $30 each , but the last ones from DD were over $100 EACH!

A new valve cover gasket might be nice , take the serial number of the engine and purchase the timing pin, you will need it eventually.

6 Air box gaskets would be nice as it is good practice to spray the piston and cylinder every winter storage.

The old US NAVY WWII training book from Grey Marine is usually under $50 on E bay and will become your Bible.


Good luck

[Lepke]

The fuel system is a circulation system. Fuel is constantly passing thru the injectors and back to the tank. So if you rig a temporary pump, you can run fresh fuel thru the injectors and make the first start easy. If you have old diesel in the tank, there'll probably be some organism growth. A good fuel conditioner with some fresh fuel will kill the growth and help combustion. The old fuel will probably burn ok, but I'd use it up before leaving on a trip.

My current boat with twin 671s sat for six years. I used a triple dose of Algae-x and 20 fresh gallons of fuel in the day tank and had no problems. I now use Archoil 6200 and I think it's better. Available online and at better fuel docks. Have some spare fuel filters.

If you disconnect the rack from the governor, you can work the rack/injectors by hand and observe the injector movement. They all should be working. If not, they usually free up without trouble. Most seaports and bigger cities have injector rebuilders. DDs are about $100 each. If you do a bunch, you can sometimes get a discount.
If the air box gaskets have dried out and are leaking, don't torque on the bolt. It's supposed to be 35 ft/lbs. Any more and it pulls the cylinder out of alignment when it's hot and causes abnormal wear. Use a sealer or new gaskets. A leaking air box cover sounds like a starter stuck in gear.
If you join https://boatdiesel.com for about $25. You have access to a library of PDFs and forums where there are Detroit mechanics.

[Arthur Garfield]

All of the above !
Get the "book" on the engine
It is a great engine
What FAST FRED said though I'd pull injectors to oil cylinders to sit for awhile then turn by hand & sit for awhile again & again... The thing here is-RINGS may have gotten "stuck" & not free sitting in pistons.Not good.There is a liquid product to help relieve this
Remember-an ounce of prevention is worth a pound of cure
Injectors prolly require new " tips" & a spray pattern examine at best.New injector copper washers for the sizing/spacing that FAST FRED mentions

Additionally,I'd be quite suspect of injector pump & O-rings-Leaky pumps suck 4 all the reasons

Big question- was engine "winterized" when put on the hard ???

Any raw water/ fresh water pump rubber impellers -just replace them out of hand

Also, any internal cam driven pump prolly should be examined as diaphragm prolly is all cracked and/or will fail quickly.


All the Best

[Cadence]

I would replace the raw water impellers, after that period before starting, they have probably dried out and you don't want pieces in your heat exchanger.

[captlloyd]

There is a traveling mechanic on YouTube that travels around working on Vintage Greyhound buses which used the 71 Series Detroit engines. Most all that he works on have been setting for awhile so he has to get them up and running. You can learn a lot about Detroit’s by watching his videos and there is a lot of them. You might do a search on Craigslist to find an independent diesel mechanic, spending a few hundred dollars on a boat like that might be a good investment. Changing oil and filters is something you can do. Detroit’s are damn fine engines, they run forever.

[GordMay]

Originally Posted by captlloyd

There is a traveling mechanic on YouTube that travels around working on Vintage Greyhound buses which used the 71 Series Detroit engines. Most all that he works on have been setting for awhile so he has to get them up and running. You can learn a lot about Detroit’s by watching his videos and there is a lot of them ...

Can you give us more clues to locating his videos?
Do Bus Grease Monkey, Technomadia, or BusTV Chanel sound familiar?

[FAST FRED]

Additionally,I'd be quite suspect of injector pump & O-rings-Leaky pumps suck 4 all the reasons.

???????

In a DD the injector IS the entire injection pump, it is operated with a push rod and rocker , just like a valve on a 4 stroke.You are thinking of a different engine.

If the injectors are not stuck , and it cranks , it will run!

To pre-oil the engine you simply pull the air box covers and squirt away. Not needed as all the internal loads are low and the geared oil pump begins to pressurize the system from the first turn of the crank.

[captlloyd]

Originally Posted by GordMay

Can you give us more clues to locating his videos?
Do Bus Grease Monkey, Technomadia, or BusTV Chanel sound familiar?

Just do a search on YouTube for, Bus Grease Monkey. Be careful, his videos are addictive if you are a gear head !

[GordMay]

Originally Posted by captlloyd

Just do a search on YouTube for, Bus Grease Monkey. Be careful, his videos are addictive if you are a gear head !

Thanks.

Bus Grease Monkey https://www.youtube.com/user/avonpicturethis/videos

[captlloyd]

Originally Posted by GordMay

Thanks.

Bus Grease Monkey https://www.youtube.com/user/avonpicturethis/videos

Great link. He has bought a nice piece of land somewhere and there is videos of him developing that lately, but just hit “ more”, there is a ton of videos on Detroit’s. If you were having issues with a Detroit this guy would be the man, buses too.