Overhauling a J&T Detroit 671N

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And not only does he have a Detroit to mess with, he has a Cessna!!!!! Is that a 170? I had a 170B.
 
jimisbell said:
And not only does he have a Detroit to mess with, he has a Cessna!!!!! Is that a 170? I had a 170B.
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It's a 140 that belongs to a friend. My plane is a LongEZ in another corner of the hangar. If he had a 170B, I'd probably try to buy it from him, I really like those.
 
Very nice and most informative thread. There's a pair of 8V71's or 92's in my future so the more vids I watch the better.

Looks like you weren't running any raw water, just kept it short enough to not get hot. Did you leave the raw water impeller out?

And, did you consider putting a filter in the fresh water system? Or are you going to flus h it out now?

Thanks.
 
oscar said:
Very nice and most informative thread. There's a pair of 8V71's or 92's in my future so the more vids I watch the better.

Looks like you weren't running any raw water, just kept it short enough to not get hot. Did you leave the raw water impeller out?

And, did you consider putting a filter in the fresh water system? Or are you going to flush it out now?

Thanks.
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Oscar,

I was not running the raw water system at all. The pump was not mounted to the engine. With the new rebuild, I really don't want to run it much, just enough to finish tuning it up and setting the idle. I put a manual temp gauge and the coolant only reached 85 degrees, the thermostat didn't even open yet.

The service manual says not to run it more than 5 minutes after a rebuild before putting a load on it. This is really common for rebuilds, you want to run them hard right away while respecting RPM limitations for the break in period. This is to seat the rings and wear them to the face of the cylinder bores. Failure to follow this protocol can result in an engine that burns more oil than desired.

I have not considered a coolant filter, I'll be flushing and replacing all of the fluids after the first few hours of use on the boat.

The 8V92 is known for having higher levels of bearing wear than the other detroits. A turbo charged 8V71 might be susceptible to that as well. This isn't a big deal but most operators replace the main and rod bearings as preventative maintenance on a schedule. This can be done in place if you can get the oil pan off, or you might have to lift the engine to do it.

For me, I really prefer the inline engines (no matter the brand) because it is easier to get to both sides of them for service and repair.

If you are interested in Detroit Diesel videos, you can't beat Bus Grease Monkey on Youtube. His channel is full of rebuilds, tune ups, service, etc... you can skip past the bus parts if you only want to see the engine stuff.

https://www.youtube.com/channel/UCTeteRfN_uu-odJld157e6Q

He did a good video of adjusting the rack a while back which was really helpful for me. I read the description in the service manual, it's a very long two page wall of text and it's really hard to understand what they are telling you to do. Seeing his video on it put all the pieces together for me. It's mainly done by 'feel' and how do you write that in a service manual?
 
Sound Great . Thanks for the video.
 
This is a bit out of sequence time-line wise if you have followed my uniflite refit thread, but I had been chasing down an oil leak that originated around the remote oil filter adapter hose fittings. I tried extra teflon tape, liquid teflon, etc... but nothing would stop the leak that appeared to be coming from the 3/4 NPT threads/hose going to the oil filter.

On close inspection, I found a crack in the casting, apparently I had over-tightened the hose and cracked the housing, I circled in it red in this photo.

i-HQ92fZC-L.jpg


This resulted in a steady stream leak. I ordered a used housing from Powerline Components, found the part number right on the casting after removing it.

The housing sits behind the oil cooler housing, so all of the coolant had to be drained. I get about 8 gallons out of it, with a couple of gallons left in the system somewhere since it holds 10. I also took the opportunity to replace the coolant drain plug.

Here you can see the housing sitting behind the oil cooler housing/heat exchanger.

i-VGX5xVP-L.jpg


I also sourced belts for the raw water pump. The J&T uses a belt driven pump and Gates Green Strip 9435 is the correct belt. It uses two in a pair.

i-xjfPS6N-L.jpg


Final assembly including the raw water pump, fuel cooler, and re-installation of the exhaust manifold will happen with the engine in the boat. The static test runs are completed, all issues addressed and the engine is now in the boat.
 
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SB, was wondering if you feel that you need that hp rating on your boat - do you find yourself running it hard and fast?

It would be quite easy to de-rate the engines a bit if you don't need all that horsepower. Running 6-71's at a continuous 60% instead of 30% (for example) makes for happy Jimmies. I had that problem on mine, ran a wee bit too low, and that big blower was cooling the block down too much.
 
makobuilders said:
SB, was wondering if you feel that you need that hp rating on your boat - do you find yourself running it hard and fast?

It would be quite easy to de-rate the engines a bit if you don't need all that horsepower. Running 6-71's at a continuous 60% instead of 30% (for example) makes for happy Jimmies. I had that problem on mine, ran a wee bit too low, and that big blower was cooling the block down too much.
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I don't really know, I've not run the boat with both engines yet, the one engine was not running when I purchased the boat. The only difference between the J&T and stock Detroit is the injectors, so some N60 injectors would put it back to stock power levels. I installed N80s per the J&T configuration as that should match up with the propeller loading curve, where the N60s would fall short.

The stock power rating from the factory was 170 hp, J&T rated it at 190HP, with the N80 injectors so if the throttle is held back a bit then the extra power isn't used. No matter the amount of power rated, running the engine hard enough to get the exhaust and combustion temps up on a regular basis will help keep carbon and other build ups at bay and is what I intend to do.
 
Perhaps I read one of your earlier posts wrong, but I was under the impression that you had the typical J&Ts which were rated way up in the 200’s or higher. It’s strange that you have a belt driven raw water pump also - is that a J&T signature?
 
makobuilders said:
Perhaps I read one of your earlier posts wrong, but I was under the impression that you had the typical J&Ts which were rated way up in the 200’s or higher. It’s strange that you have a belt driven raw water pump also - is that a J&T signature?
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No these are just 671N motors, no turbo or anything. They should be pretty long lived as is. I haven't seen any other 671 with belt driven raw water pump, I think it's fairly unique but it is the way J&T did them
 
sbman ... I left you a PM on THT ... I'm all caught up now reading your three different threads here ... a seriously impressive effort you have mustered I gotta' say ... so, moving onward ... back in your post #82 in this thread, you spoke about re-usable hydraulic fittings and bulk hydraulic hose for your fuel, oil and trans cooler lines ... would you mind elaborating on the brand name(s) of the hose / fittings and / or the name of the hose shop that figured out what worked with what for you? Up here in Vancouver, Canada, I have Green Line or New Line to deal with ... I just can't seem to find what I need with them.

I have the identical boat (mine's a '79) & near identical engines as you (Industrial 6-71N engines [white in color] marinized by PACIFC DIESEL POWER CO., with San Juan Engineering (/ Seakamp) h.e.'s and rear-mounted, gear-driven JABSCO raw water pumps) ...

I'm going to make some changes to my existing engine oil pan-mounted quick-drain valves ... currently I have mis-matched 1/2" F/F NPT brass ball valves (plugged by clear silicone-sealed 1/2" M NPT carbon steel plugs [3/8" dr. sq. int.]), each mounted to 1/2" M/M NPT brass nipples in the oil drain holes of my oil pans ... I have found I cannot get near the outboard (left side) mounted quick-drain valve on my Port engine and (once I've battled to reach it once and drain the engine oil) want to run a length of steel-braid hose from a 90° (swivel?) fitting at the oil pan drain hole (Port engine ... and perhaps a straight fitting / shorter length of hose for the Stbd engine, whose inboard [left side] pan drain hole is far easier to access in the e.r. aisle).

I have not decided exactly how to terminate these hoses in the e.r. aisle ... there are some pretty slick oil change systems available ... i.e. GROCO ($1K USD) or X-Change-R ($649USD) ... however, perhaps I'll just stick with (plugged, for security) ball valves at the hose termination points in a convenient spot in the e.r. aisle. I do have a JABSCO 17800-2000 bucket-mounted oil change system (it was used with a 1/4" x 40" dipstick probe that I now cannot locate) whose pump could be easily adapted to draw / drain and pump used engine oil from the un-plugged ball valves at the hose ends into empty 5 gallon pails as required.

What kind of an engine oil drain system did you elect to go with?

FFF
 
Frankenstien said:
sbman ... I left you a PM on THT ... I'm all caught up now reading your three different threads here ... a seriously impressive effort you have mustered I gotta' say ... so, moving onward ... back in your post #82 in this thread, you spoke about re-usable hydraulic fittings and bulk hydraulic hose for your fuel, oil and trans cooler lines ... would you mind elaborating on the brand name(s) of the hose / fittings and / or the name of the hose shop that figured out what worked with what for you? Up here in Vancouver, Canada, I have Green Line or New Line to deal with ... I just can't seem to find what I need with them.

I have the identical boat (mine's a '79) & near identical engines as you (Industrial 6-71N engines [white in color] marinized by PACIFC DIESEL POWER CO., with San Juan Engineering (/ Seakamp) h.e.'s and rear-mounted, gear-driven JABSCO raw water pumps) ...

I'm going to make some changes to my existing engine oil pan-mounted quick-drain valves ... currently I have mis-matched 1/2" F/F NPT brass ball valves (plugged by clear silicone-sealed 1/2" M NPT carbon steel plugs [3/8" dr. sq. int.]), each mounted to 1/2" M/M NPT brass nipples in the oil drain holes of my oil pans ... I have found I cannot get near the outboard (left side) mounted quick-drain valve on my Port engine and (once I've battled to reach it once and drain the engine oil) want to run a length of steel-braid hose from a 90° (swivel?) fitting at the oil pan drain hole (Port engine ... and perhaps a straight fitting / shorter length of hose for the Stbd engine, whose inboard [left side] pan drain hole is far easier to access in the e.r. aisle).

I have not decided exactly how to terminate these hoses in the e.r. aisle ... there are some pretty slick oil change systems available ... i.e. GROCO ($1K USD) or X-Change-R ($649USD) ... however, perhaps I'll just stick with (plugged, for security) ball valves at the hose termination points in a convenient spot in the e.r. aisle. I do have a JABSCO 17800-2000 bucket-mounted oil change system (it was used with a 1/4" x 40" dipstick probe that I now cannot locate) whose pump could be easily adapted to draw / drain and pump used engine oil from the un-plugged ball valves at the hose ends into empty 5 gallon pails as required.

What kind of an engine oil drain system did you elect to go with?

FFF
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I have the same issue with the oil drains, mismatched threads and ball valves, one of which I can't reach. I have not sought a solution yet.

When I took an old hose into the host shop, the guy took one look at it and said 'Oh thats Parker such and such' and pulled out identical looking hose from behind the counter. It fit perfect in the existing fittings and does not leak or have any issues. Post a pic of the hoses you have and their fittings and I'll find out what the model of hose is that I was able to use. I know it is Parker hose, I'm just not sure which series.
 
Hey sbman ... that was quick!


So, there's no hoses currently rigged on my oil pan quick-drain valves ... I have the luxury of starting fresh for this particular application ... I'm thinking I'll re-vamp the existing nipples / valves with whatever my permanent solution entails ... FFF
 
On our 6-71N there was no oil drain ball valve, a screwed in 90deg was connected to a good hose. The hose was long enough 5 6 ft? to be easy to reach in the engine space.

The hose was capped with a hydraulic quick disconnect, which could clip into another hose on a manual rotary aircraft fuel pump, but a rotary drum pump would work as well.

Never fun going down to the engine space after a long days run , but with 2 - 5 gal oil cans ready , each got 4 gallons quickly , and could be removed at leisure when recycling the old oil.

Safe , fool proof, cheap , and clean .
 
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Well ... FYI sbman & FF ... I just finished pricing out a couple of custom SS braid hose (SAE100R14 PTFE Lined 304 Stainless Braided / Standard White Tube) assemblies with brass 90° live swivels at the oil pans and SS-capped, compact 316 SS ball valves at the other ends of the hoses ... and the fittings, although 316 SS, were crimp-on and not re-useable ... forget it ... over $550CAD + 12% taxes ... I think I'll do something simpler like what FF did ... FFF

follow-up edit: I should mention that sourcing stuff like what I described above in Canada is akin to being way out in the sticks ... not a lot of choice in terms of vendors or what's available ... when I was moored at Point Roberts Marina, I could online order almost anything from the lower 48 and a couple of days later, just saunter over a couple of blocks and pick it up ... now with the pandemic, that option is curtailed for the foreseeable ...
 
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That price is inline when I checked into having new, crimped hoses made for the Detroit. I was happy the engine has re-usable fittings and only one was rusty and had to be replaced.

The Parker brand reusable fittings in plain steel run about $20-$30 each depending on type and size and hose varies but for 1/2" I think it's around $15/ft for composite braided medium pressure hose (around 1500 PSI) so that same configuration would be probably around $85-$100 for each assembly (assemble yourself) plus ball valves and they'd need to be painted.

Have you figured out what the thread is on the oil pan? I need to do something about the starboard engine's oil drain before I put the exhaust back on.
 
Frankenstien said:
follow-up edit: I should mention that sourcing stuff like what I described above in Canada is akin to being way out in the sticks ... not a lot of choice in terms of vendors or what's available ... when I was moored at Point Roberts Marina, I could online order almost anything from the lower 48 and a couple of days later, just saunter over a couple of blocks and pick it up ... now with the pandemic, that option is curtailed for the foreseeable ...
Click to expand...

I guess I should be happy with availability in San Diego. I often complain to myself that it seems like everything has to come out of Los Angeles but it's actually not bad, most stuff can be had next day. The hydraulics I can get walk in service at my local hose shop for most common stuff.

These guys are where I've purchased the Parker fittings and hoses, in person:

https://www.hoseandrubberproducts.com/
 
FF said:
On our 6-71N there was no oil drain ball valve, a screwed in 90deg was connected to a good hose. The hose was long enough 5 6 ft? to be easy to reach in the engine space.

The hose was capped with a hydraulic quick disconnect, which could clip into another hose on a manual rotary aircraft fuel pump, but a rotary drum pump would work as well.

Never fun going down to the engine space after a long days run , but with 2 - 5 gal oil cans ready , each got 4 gallons quickly , and could be removed at leisure when recycling the old oil.

Safe , fool proof, cheap , and clean .
Click to expand...

This sounds ideal, there is no point low enough to drain the oil by gravity anyways unless you put something very low profile below the engine. Pumping it out and into buckets would be the way to go.
 
sbman ... those oil pan drain hole threads should be 1/2" FNPT ... mine have brass 1/2" MNPT close nipples in them with bronze (Port) / brass (Stbd.) FNPT / FNPT ball valves threaded onto the close nipples ... then they plugged the ball valve outlets with carbon steel plugs (3/8" sq. dr.), using clear silicone sealant, and, evidently, never used them again (or much). I'm basing the latter on the JABSCO 17800-2000 Porta Quick Oil Changer (pump mounted to bucket lid) system that was left onboard for me by P.O. ... it was used with a dipstick probe that is now MIA. FFF
 
Frankenstien said:
sbman ... those oil pan drain hole threads should be 1/2" FNPT ... mine have brass 1/2" MNPT close nipples in them with bronze (Port) / brass (Stbd.) FNPT / FNPT ball valves threaded onto the close nipples ... then they plugged the ball valve outlets with carbon steel plugs (3/8" sq. dr.), using clear silicone sealant, and, evidently, never used them again (or much). I'm basing the latter on the JABSCO 17800-2000 Porta Quick Oil Changer (pump mounted to bucket lid) system that was left onboard for me by P.O. ... it was used with a dipstick probe that is now MIA. FFF
Click to expand...

That's interesting. I figured the threads in the oil pan would be a straight thread and be expecting a copper washer type gasket to make the seal. I assumed the NPT fitting that is currently in there was not an exact match so I used a good amount of teflon tape with the close nipple that is currently in mine.
 
Frankenstien said:
Hey sbman ... that was quick!


So, there's no hoses currently rigged on my oil pan quick-drain valves ... I have the luxury of starting fresh for this particular application ... I'm thinking I'll re-vamp the existing nipples / valves with whatever my permanent solution entails ... FFF
Click to expand...

FFF

When I did my engine swap 20 yrs ago, I had the oil drain hoses added. They were designed to fit the bung in the bottom of the oil pan, which they fit exactly, so no Rube G required. I got mine from Inlet Marine in Port Moody. Inlet is still my "go to" for all things engine.
 
sbman ... I should clarify that I have yet to physically confirm the oil pan drain hole threads ... from what I can see on my Port engine, a conventional brass 1/2" MNPT close nipple is being used (no copper washer or even sealing compound / tape visible) ... I have yet to uninstall the FNPT/FNPT ball valve that's there and won't ... until and unless I decide on drain hose assembly pieces ... however, another affirming indicator as to the nature of the O.P.D. threads is in this EZ OIL DRAIN VALVE chart I found online, which specifies EZ-202 for DD Series 71, an NPT 1/2”-14 threaded item..

koliver ... thanks for the suggestion ... I spoke to Martin in Parts and Sean in Service at Inlet Marine ... they explained they had nothing off-the-shelf and, if they were to undertake the work for me (except that I do as much of my mech. work as possible, this type of project being a good example), would be faced with cobbling together the drain hose pieces in much the same fashion as I have already done ... my initial laundry list of premium pieces was just too much $ ... I'll need to simplify matters or defer the notion. FFF
 
Frankenstien said:
sbman I have yet to uninstall the FNPT/FNPT ball valve that's there and won't ... until and unless I decide on drain hose assembly pieces ... however, another affirming indicator as to the nature of the O.P.D. threads is in this EZ OIL DRAIN VALVE chart I found online, which specifies EZ-202 for DD Series 71, an NPT 1/2”-14 threaded item...
Click to expand...

I looked up replacement drain plugs and they are listed as 1/2 PIPE so it looks like that's what it is.

https://www.powerlinecomponents.com/catalog/detroit-diesel-71/127/oil-pan

I'll likely put a bronze fitting there and go to a high quality hydraulic hose/quick disconnect as described by FF that I can use to pump oil out and back in with.
 
sbman ... are these Parker hydraulic hose/quick disconnect couplers & nipples even close to what you're thinking of?

I selected the 'Brass' & '1/2-14' filters to pare things down a bit ...

Parker offers so many different Quick Couplings Hydraulic for various applications that the ones I reference above may not be at all appropriate, or, are possible total overkill (i.e. don't need 2200 psi capability) ...

And, as far as the Parker reusable ('live swivel' possible?) hose fittings are concerned, do you remember the product descriptors (or have part numbers?) for what you've been using? Parker's online selection process is complicated by their vast number of choices. I went to HRP's site but again quickly got lost with all the choices offered.

Thanks, FFF
 
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When purchasing hose or fittings for hose the swiveling version costs a bit more but is worth the cost.
 
Frankenstien said:
sbman ... are these Parker hydraulic hose/quick disconnect couplers & nipples even close to what you're thinking of?

I selected the 'Brass' & '1/2-14' filters to pare things down a bit ...

Parker offers so many different Quick Couplings Hydraulic for various applications that the ones I reference above may not be at all appropriate, or, are possible total overkill (i.e. don't need 2200 psi capability) ...

And, as far as the Parker reusable ('live swivel' possible?) hose fittings are concerned, do you remember the product descriptors (or have part numbers?) for what you've been using? Parker's online selection process is complicated by their vast number of choices. I went to HRP's site but again quickly got lost with all the choices offered.

Thanks, FFF
Click to expand...

I'm going to go over to HRP today and get the parts to setup mine. I'll share the part numbers once I've got it. I want to get that in there so I can complete the engine installation, once I put the exhaust on it will not be accessible.
 
Roger that ... thanks sbman ... if those reusable fitting / hose part numbers aren't buried too deep, that'd really help me out too. FFF
 
Here's the stackup of what I ended up getting, in order of assembly from starting at the oil pan:

2404-8-8 - (Unknown brand) 1/2" NPTM to 1/2" JIC Adapter $3.64
23920-8-8 - (Parker) Two piece field assembly Female 90 deg JIC Hose #8 Fitting $30.21
201-8 - (Parker) Hose, -8 201 Series (13/32") - 6 feet $64.80
20120-8-8 - (Parker) Two piece field assembly -8 Hose to 1/2" Male NPTM Fitting $20.51
H4F4 (Dixon) Male H Series Hydraulic Quick Connect 1/2 NPTF $23.11
4H4D - (Dixon) Female H Series Hydraulic Quick Connect 1/2" F NPTF $59.27

Everything is rated to 2000 PSI working pressure and is rated for oil and high temperature. All fittings are steel, although most are available in other materials as well.

i-VrX3F2F-X2.jpg


Hose: https://ph.parker.com/us/en/rubber-cover-transportation-hose-201/201-8

20 Series Fittings:
https://ph.parker.com/us/en/20-series-fittings
The specific fittings I am using:
https://ph.parker.com/us/en/20-series-fittings/20120-8-8
https://ph.parker.com/us/en/20-series-fittings/23920-8-8

The quick connects are made by Dixon and are not cheap. It was $60 for the Female one but I only need one of those, I'll put the male ends on each engine at $30 each. The Female quick connect is pretty big at with the locking ring almost 2" in diameter.

That makes it about $140 per engine plug the female disconnect to put on whatever oil change pump you are using at $60.

I plan to put some permanent plumbing in the boat and mount a pump in the engine room to do oil changes with. I am thinking of going with a Marco UP2 reversible gear oil pump that I saw in another thread.
 
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