Smoke out exhaust dissapears when in gear?

[er9]

So i have an older Universal 5432 in my boat. it has its issues and needs attention. it does run ok and starts immediately but one issue that i'm curious about the most iv'e noticed recently.

Since iv'e bought the boat the engine has a thick smoke from the exhaust when you start it. the smoke continues from the exhaust after starting it. it doesnt seem to dissipate or go away however...as soon as i put the boat in gear and begin motoring out the smoke pretty much disappears completely and is soon replaced by steam (definately not white smoke). there still is very light smoke after i begin motoring, i really can hardly see it though. i see a small amount of steam though.

curious if there is an obvious cause for such a thing or is it just a symptom of something larger. the smoking and steam definately are issues and i plan to try addressing the steam issue starting today but curious if anyone had any insight on why the smoke might disappear when going into gear?

[a64pilot]

Is it blue smoke, and smells of oil, or is it a lighter color and has an eye burning sulphur smell?
First is oil and as an engine gets older it is normal for it to get some leakage by the valve seals and smoke a little til it burns off, being under a load raises exhaust temps and can burn it off quicker. I'd ignore it, it can be years before it gets bad enough to need attention, fix is to have head rebuilt, new valve seals really, but if they are old and hard, time for a valve job too most likely.
The other is fuel and usually points to injectors needing cleaning or possibly tips replaced, if you don't know when that was last done, its due. Bad spray pattern isn't good for an engine, results in carbon build up, carbon is very abrasive and does shorten engine life somewhat.
The steam could point to a restriction in raw water flow, and even if engine doesn't overheat, it could be ruining your muffler and exhaust hoses due to excess temp. Tremendous amount of energy in steam of course, it was once used to drive ships


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[tkeithlu]

From your description you have a properly starting and motoring engine, but white(?) smoke/steam? Could it be that your wet exhaust isn't getting enough water at startup and low RPM?

By the way, it's a Kubota engine. I have an old Universal M25 that faithfully runs my 6.5 KW generator. Westerbeke bought Universal and wants $1,164.95 for a starter. The Kubota price is $68.80. If you have to work on your engine, do a little research to find the Kubota twin and get your parts there.

[er9]

Originally Posted by a64pilot

Is it blue smoke, and smells of oil, or is it a lighter color and has an eye burning sulphur smell?
First is oil and as an engine gets older it is normal for it to get some leakage by the valve seals and smoke a little til it burns off, being under a load raises exhaust temps and can burn it off quicker. I'd ignore it, it can be years before it gets bad enough to need attention, fix is to have head rebuilt, new valve seals really, but if they are old and hard, time for a valve job too most likely.
The other is fuel and usually points to injectors needing cleaning or possibly tips replaced, if you don't know when that was last done, its due. Bad spray pattern isn't good for an engine, results in carbon build up, carbon is very abrasive and does shorten engine life somewhat.
The steam could point to a restriction in raw water flow, and even if engine doesn't overheat, it could be ruining your muffler and exhaust hoses due to excess temp. Tremendous amount of energy in steam of course, it was once used to drive ships


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thanks...its a bluish/white smoke and smells of diesel exhaust. pulled raw water filter yesterday and all was clean. next stop is heat exchanger to see if blockage. it seems like the same amount of water exits the exhaust as my friends boat which runs normal. she has a different engine though. i havnt owned it long enough or have the experience to know what the water flow/running characteristics were when it was newer. temp gauge stays at even 160ish.

[er9]

Originally Posted by tkeithlu

From your description you have a properly starting and motoring engine, but white(?) smoke/steam? Could it be that your wet exhaust isn't getting enough water at startup and low RPM?

By the way, it's a Kubota engine. I have an old Universal M25 that faithfully runs my 6.5 KW generator. Westerbeke bought Universal and wants $1,164.95 for a starter. The Kubota price is $68.80. If you have to work on your engine, do a little research to find the Kubota twin and get your parts there.

as i rev the rpm's while motoring i will have to keep an eye on amount of water exiting exhaust. from recollection it seems to stay fairly constant although i think i do run the engine at lower than i should rpm's. no rpm gauge.

yeah thanks for info. im slowly becoming hip to the fact about parts pricing. insane what the marinized parts cost never mind the non marinized stuff.

[tkeithlu]

Be glad you're running diesel, not gasoline. Then the prices are necessarily outrageous because they all have to be spark proof.

Are you ready to tackle this engine? Have you got a mechanic as backup? A diesel in proper repair shouldn't throw blue-white smoke - it should throw virtually invisible smoke, independent of any problems in the exhaust system. Most of the sources of white smoke are not going to be good news - they are related to serious engine wear. I think that if I had this problem, and did not want to simply ignore it (a real choice - there are plenty of trucks on the road in much worse shape), I'd pull the injectors and check the compression in each cylinder. If you've got a low one then it's head/valve and maybe even full overhaul/rings time. In that case, the smoke may be lube oil collecting in the cylinders before you start. Ever see the smoke from radial aircraft engines when they start? - that's oil collected in the lower cylinders. Ouch. But, hopefully, compression is OK and the injectors need cleaning or rebuilding. Injectors can be checked by filling them with WD-40 and then rapping them on the top with a wooden or copper mallet - they should bounce on their springs and spray a fine mist of oil out their jets. Sometimes that actually cleans them. Do not, however attempt to put anything in those tiny holes - you'll damage them. Send them off for rebuild or buy some spares at that point.

If you decide to tackle it, you will learn a lot about diesel engines in the process. If you want a starting point for understanding it, Nigel Calder has a good section on it in Boatowner's Mechanical and Electrical Manual including possible causes for various smokes.

[er9]

hey thank you for all of that. its a pretty old engine and original to the boat. my suspicion is that the previous owners did sort of regular maintenance to keep it running but besides a new water pump, i believe nothing major so far as rebuilding has ever been done. i knew this going into the purchase so is not a surprise.

a guy i know at work said almost exactly the same thing about the injectors. high up on my list of things to do. the smoke does burn off fairly quickly once i put it in gear and start motoring out of the slip. usually by the time ive backed out of my slip the smoke is gone and very hard to see.

all that being said, i did just purchase that book and have started reading it. i plan to do a complete rebuild of the engine early next year. the bottom hull needs paint first and is priority but i plan to do the rebuild myself with help when i need it. loooking forward to it....well not the dollar cost but the mechanical. will try cleaning/checking/rebuilding the injectors first though. more than one person has suggested they are a culprit in the problems i am having.

thanks again for the advice and suggestions.

[a64pilot]

I would first determine oil pressure compared to specs and compression.
And if compression is low, determine with a leak down test if it's a valve or not.
Your engine may have a lot of life left in it, or may be on it's last legs.
I would not rebuild just for the heck of it before determining if it needs it.
I rebuilt my airplane engine years ago as It was closing in on TBO (time between overhaul) and to speed things up I bought all new cylinders etc so that I already had parts on hand to speed the overhaul. Long story short when I sent the crankshaft and other parts off, everything met new specs, not serviceable specs, but new. Other than resetting the TBO clock all I did really was waste lots of money and considerable time overhauling something that didn't need it.

[model 10]

Originally Posted by a64pilot

Long story short when I sent the crankshaft and other parts off, everything met new specs, not serviceable specs, but new. Other than resetting the TBO clock all I did really was waste lots of money and considerable time overhauling something that didn't need it.

That's going too far. The bearings for example were not in new condition. You also didn't know everything was in such good condition until you took it apart. Pretty much the intent of having a TBO in the first place. Safety first.

[four winds]

I suspect A64 was referring to the journals and other load brearing surfaces, not the bearings themselves.

I suspect new bearings were installed.

[a64pilot]

Honestly, I didn't even look at bearings, they are expendable items, I think of them like gaskets.
I just sent the crank off, didn't look very hard, it was magnafluxed, measured and journals polished, didn't look at cam either, had it and the lifters re-ground. Where I screwed up was buying new Millennium cylinders at a grand ea for six, I should have inspected the old cylinders but didn't, about a $5,000 mistake as old ones were fine, just hone and new rings. New owner got himself a good engine.

FAA definition of an overhaul, is disassemble, clean and inspect. Of course replace what doesn't meet overhaul specs.
What this has to do with a boat, is measure first, buy parts after your sure you need them, age or even hours unless excessive is not necessarily determine need for an overhaul.
If oil pressure is good, oil consumption not too excessive and good compression, why overhaul?

[model 10]

I just finished an "overhaul" of a Perkins 107. It was a 1972 with 4500 hrs. The main bearings could have been re-used along with 3 of 4 rod bearings. For some reason 1 cylinder had stuck rings and worn rod bearings. The rest of the engine could have lasted forever.
Putting a load on the engine causes the combustion chamber temp to rise so it burns things better and you get less smoke.

[Dave the Canuck]

Check the mixing elbow as well. If partially blocked, as is very possible on that vintage Universal, it could produce the symptoms you describe. Simple and cheap fix if that's the case.

Good luck!

[er9]

Originally Posted by a64pilot

I would first determine oil pressure compared to specs and compression.
And if compression is low, determine with a leak down test if it's a valve or not.
Your engine may have a lot of life left in it, or may be on it's last legs.
I would not rebuild just for the heck of it before determining if it needs it.
I rebuilt my airplane engine years ago as It was closing in on TBO (time between overhaul) and to speed things up I bought all new cylinders etc so that I already had parts on hand to speed the overhaul. Long story short when I sent the crankshaft and other parts off, everything met new specs, not serviceable specs, but new. Other than resetting the TBO clock all I did really was waste lots of money and considerable time overhauling something that didn't need it.

thanks...good point. i will do these things first. i'd like to not rebuild it if i dont have to. i could use that $$$ for many other things for sure.

[er9]

Originally Posted by Dave the Canuck

Check the mixing elbow as well. If partially blocked, as is very possible on that vintage Universal, it could produce the symptoms you describe. Simple and cheap fix if that's the case.

Good luck!

check, now on the list of things to do. will attempt heat exchanger in coming weekend first as zinc on exterior of exchanger looks like it has a white mushroom colony growing on it. not looking forward to either as access is worse than horrible.