Dead Detroit 671

syd

syd

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Boat's in Chatham, I'm in Essex
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Just bought a 30 year old Bertram 42 with twin Detroit 671 two stroke turbo engines. First trip was getting it home, 13 hours at sea without a problem. Got into harbour and starboard engine petered out and died. Still showing a quarter tank of fuel. Filled up with more fuel in case gauge was wrong. fitted new filters,Re filled filters, it fired up for a short time then died again. Checked fuel line and found it blocked, cleared fuel line, re filled filters and it did the same, ran a short while and died, checked flow o.k. filled filters again and getting nothing, engine spinning over but no firing. Is there something I'm missing? Does something else need bleeding ? I'm told these are self bleeding.
 
Bleeding / Priming .....

syd said:
.........Does something else need bleeding ? I'm told these are self bleeding.
Click to expand...


Yes, in principle these are self priming....and the injectors can handle a fair bit of air... however, if there is nothing in the pipes, there is nothing to generate the suction from the filters to the fuel pump... and you have probably sucked everything dry.

So the thing to do is:

1) at the top-side of the aft fuel fiter canister (presume you do not have spin-on conversion here) there should be a bolt (a plug often holding a fuel hose as well).

FuelCannister-1.jpg


Remove this and use a biggish syringe ... get them at chandlers.. (or something you can fill up with diesel and which generates some sort of seal where the plug fits in). Fill up the filter cannisters thrugh this and then it becomes a bit messy....

Basically you need to use the syringe to force fuel upwards to the fuel pump,.... so you need to be able of filling the syringe, force fuel up the way (as much as you can ...by repeating the process without spilling to much... (so finger ready to plug the hole :) :) whilst you repeat the process...) ...perhaps half a litre or so .... then replace the plug (without spilling too much :D :D :D)...

Then you should have enough for the pump to push the excess air through and you will have clean fuel to the fuel rack... :D

Good luck...
 
A pleasure...

Nice engines to work on, presume they are handed as well, so all service items in centre.

Bet that one is a bit slower starting than the other ... (once this is fixed that is). ...One will be Left Rotating and the other Right (takes a while to get head around that one as some parts are not interchangable)... Allison M15 gearboxes should give a very smooth gearchange... Parts are cheap (refurb injectors at approx £40... makes for happy boating).
 
Forgot to mention ... never .... I mean NEVER !! use multi-grade oil in the engines or gearboxes.

This will only result in Big Bill arriving...

Straight 40, at appropriate spec. is right. Get this from most fuel suppliers at very good rates (seem to recall that I paid about £130 for 60 L about a month back)...(the sump is about 25L on each engine...),
 
Jentex Canterbury Road West, Cliffsend, Ramsgate, Kent CT12 5DU,

Should be able of supplying.... and 3 litres is not much, so should be OK... but stop topping up with this stuff... these engines fire twice as often as a "normal" engines and the compression rings are of a slightly different design than of the four strokes( and have tight tolerances), which cause a slicing action on the oil, which breaks down multi-grade oil (don't ask me about the technicalities).

... one of the better ones to get is Chevron's DELO 1000 W40 approved by Detroit recommended for use in engines burning marine diesel oils with a sulfur content of up to 1.5%, but plenty of others around...

I've got a 800 page workshop manual for our 6/71's, scanned to PDF format, which is word searchable if you are interested.
 
Manual

That would be a great asset. I'm familiar with Penta's and Mercruisers but never come across a configuration like this. You're right about the sided engines, its mad and very convenient, all the important bits are in the middle of the engine bay.
If you're passing the inner marina at Ramsgate look out for Arista, pop in I'll buy you a drink.

Syd
 
Divemaster1 said:
Jentex Canterbury Road West, Cliffsend, Ramsgate, Kent CT12 5DU,

Should be able of supplying.... and 3 litres is not much, so should be OK... but stop topping up with this stuff... these engines fire twice as often as a "normal" engines and the compression rings are of a slightly different design than of the four strokes( and have tight tolerances), which cause a slicing action on the oil, which breaks down multi-grade oil (don't ask me about the technicalities).

... one of the better ones to get is Chevron's DELO 1000 W40 approved by Detroit recommended for use in engines burning marine diesel oils with a sulfur content of up to 1.5%, but plenty of others around...

I've got a 800 page workshop manual for our 6/71's, scanned to PDF format, which is word searchable if you are interested.
Click to expand...

VI - or Viscosity Improvers are long chain "coil" type molecules (styrene-butadiene copolymers) that "uncoil" themselves as the temperature of the oil increases. Normally very good, but as you say, the slicing action of the rings ruins this effect.
 
syd said:
That would be a great asset.........If you're passing the inner marina at Ramsgate look out for Arista, pop in I'll buy you a drink.....
Click to expand...

Send me a PM with your address and I'll post a CD to you .... (it's a 37 MB file, so a bit big to e-mail) ... alternatively I can post it on www.yousendit.com, but I will ned to register (free trial) .....will need your e-mail address ... so PM me that.

Would be great to "pop down" for a chat and see the newly aquired lady, but it is a 620 Mile drive, so may be a bit of a push this week-end... :D
 
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