Caterpillar 3208 Smoke

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WKleiser

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Aug 23, 2019, 10:19:27 AM8/23/19
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Our 1979 40' has the 3208N engines.  My issue is the smoke from these engines, especially on startup .  The engines are sound, use no oil, and run very well.  However, even warm if you look closely you can see a small bit of smoke (unburned fuel).   I've asked a couple mechanics and they shrug and say it's typical.  However has anyone had experience with the impact of changing injectors and adjusting the valves  having an impact?   I'm tempted to do this just to see if my smoke goes down but would like to know what others experiences have been with injector services, valve adjustments etc.


dav...@msn.com

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Aug 23, 2019, 12:37:36 PM8/23/19
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I don’t have cats, but I have had the same smoke issue with my Volvo’s. I found that it was an injector issue. I had them removed and sent down to Seattle Injector for testing, cleaning and adjustment. I had a couple that were way out of spec which probably caused a lot the smoke. That solved my problem. Seattle Injector charges about $120 per injector so it’s not cheap, but well worth it.

Pete Jung

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Aug 24, 2019, 7:26:06 PM8/24/19
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Hi WKleiser,

I've got same engines in my similar-vintage Tolly 48.  They also smoke upon cold start.  However, HOW MUCH smoke is a subjective issue!  With new injectors three years ago, mine start at first roll, but have visible smoke for about ten minutes, then run cleanly until shutdown.  And yes, there's a small residual oil film left on the water after shutdown.  As with all mechanically injected diesel engines, they are over fueled at startup by design-hence the smoke.  So sometimes, start smoke has nothing to do with either the injectors or valve adjustment.  Should you feel your smoke issues are intolerable, little to do besides general CAT maintenance (including routine valve adjustment), injector service, injection pump inspection, pump timing and/or rebuild, etc.  Our engines are 40+ years old.   For better or worse, they don't act like, nor run like modern common-rail engines.  

Regards,

Pete


WKleiser

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Aug 24, 2019, 9:59:13 PM8/24/19
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Pete, I'm curious if you got any noticible reduction in smoke when you did service your injectors (sounds like 3 years ago)?  

We don't have any operational issues otherwise, the engines s start very easily (generally on the first compression), run smoothly, don't seem to use any oil etc.  What's bugging me is that if you look closely, even when warm there's small amout of visible smoke.  THe combination of diesel odor and the stern exhaust, which causes the fumes to be sucked along behind the boat, renders the cockpit fairly unpleasant when running.   
Bill

Steve Kraus

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Oct 8, 2019, 8:19:24 PM10/8/19
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Did you determine if your 1979 Cats are actually pre 3208’s?

WKleiser

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Nov 11, 2019, 1:47:33 AM11/11/19
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They're 3208s.   

Steve Kraus

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Nov 11, 2019, 11:20:33 AM11/11/19
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The reason for the original  question ( Are  the 1979 Cats really 3208's?)  is as follows: 
            Often there is a perception of commonality between the original CAT 3160 engine and the subsequent model 3208, since they basically appear the same . In fact, many never heard of the Cat  3160, which was the first iteration of the 636CID Cat 3208. 

Over time, the 1970's vintage Cat 3160 engines were usually called 3208's  ( when there are distinct  differences that influences problem diagnosis and resolution. ( like 

the fuel delivery system AND the substandard piston rings to manage blow-by. These of course  differentiate  problem resolutions among ALL the  636CID V-8's ESPECIALlY excess exhaust smoke.

Occasionally customer's  were surprised to find what they thought was a yellow 3208,  actually I.D.'d to be an original 3160 engine by Ser. #.

Thanks for reading.
Steve


Marc Talley

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Nov 11, 2019, 12:51:37 PM11/11/19
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Steve,
You are The Best!
Will you be up here this Summer?

WKleiser

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Nov 12, 2019, 1:16:36 PM11/12/19
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Ah, well, I'll have to check with North Harbor Diesel, they've worked on the engines and may have noted the Serial Numbers.  I've never found the SNs myself but haven't looked all that hard.   I understand you can also look at the FI pump for a clue as to 3160 vs 3208.  My understanding though was that the move to the 3208 took place in 1976. 

 Admittedly what I consider excess smoke may be subjective, the mechanic who surveyed the engines thought they were fine since visible smoke mostly is gone when they're fully warmed up.  But the first 10 min of operation it seems high to me.  Of course the stern exhaust compounds the problem by sucking exhaust along with the boat.   

The mechanic who did the sea trial had suggested that we should run the engines up to near max RPM occationally, but with our towed skiff that wasn't possible this summer, we cruise around 1600RPM and the max we can do with the skiff behind is around 2000 rpm.   When we sea trialed last December they ran them up to 2800RPM but without a skiff the wake wasn't an issue.   

Steve Kraus

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Nov 15, 2019, 10:49:16 PM11/15/19
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Marc, 
Thanks for thinking of us. Roz and I will be there and we WILL see you.

I sent you a seperate private em a few days past. 
Lots of catching -up to enjoy......
I think I mentioned, now have a 30' and a 26' Tolly w/ daughter .
Thank you
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