3.0GSMBYMCE smoke from PCV (& thus through carb), 30 psi oil pressure (& dieseling)

[mnjjansen]

3.0GSMBYMCE smoke from PCV (& thus through carb), 30 psi oil pressure (& dieseling)

Volvo Penta 3.0GS MBYMCE Noticed after shutdown : dieseling, smoke coming from flame arrestor / PCV valve pulled : coming from a top of the cylinder head. Seems engine is hot. Watertemp. ok, full pressure, temp between 85 degrees celcius which is ok. Block seems warm though.

Observations during run :
* Engine runs normally steady at 40 PSI oil pressure, now at 30PSI
* Noticed scratching sound above 3500 rpm
* Idle, carb runs around 1000 rpm after operating temp (bit high but deliberately set to take off)
* Carb is 1997 GL OEM version (2300 but with 63 sized main jets), seems however to run rich.However, never altered and has run great with the settings as is.
* WOT 4200 rpm which is line with this carb. vs 4600 rpm with 71 or 75 main jets,
* > 3500 rpm scratching sound (like I remember from oil passing piston rings) : but NO oil leakage anywhere
* oil levels ok, oil visually ok. Also no water intake.
* Trimming during run made more excessive sound,, might however come from alternator who tends to 'scream' (bearing) often when I use powertrim but normally when cold. Did notice 3 hand full of waterplants approx. hanging at my drive.
* No external leakage (oil, water, fuel).

Changes done before going off :
* During my former run my PCV jumped out the rubber "shell" so I put some tape around (and yes, not to close it ...) the PCV to keep it in place, which it did. But perhaps I shouldn't ? Normally it ticks like hell but it didn't now because I sealed it well around but again not on in the intake side.

I let the engine idle for approx. 60 second before shutting down as I know it diesels sometimes. However, not used that smoke is appearing from the oil on top of my cylinderhead, however clean oil on top. Then together with the scratching sound > 3500 rpm : I get concerned.

Suggestions ? Thank you. Unless you're heavily occupied you might enjoy to read the following, just for laughs.

Now you're not going to believe it, but in one year this is my fourth 3.0L GM block (under warranty) and finally I got an engine with no leaks :
block 0 : "original" engine with automotive parts...do not to tell more .... but this shitty engine got me up to 4860 rpm (carb!) .... until water intake.

...... that's the moment you install a new engine 10k euro in The Netherlands (revision hell no) , or start learning and find your way around and learn the 'value' of self acknowledged mechanics.. or better start reading yourself .... and then you got a theoretical grip, .....then you learn the value of experience ... and then iBoats.... c'mon). But still enjoyable aside the financial matters but anyhow :

Then the story unfolds :
block 1 : mechanic installed oversized block cylinders vs pistons : this is how I learned scratching sound and oil jumping all around the place. Real fun ;
block 2 : new exhaust manifold gave away , cracked (water intake) : full engine overhaul (I always assume water getting in the oil pan over the piston rings : so yes full overhaul with a engine immediately taken apart still 750-900k euro per event) ;
block 3 : yes, new exhaust manifold gave away again. Wtf. NO Barr foundry quality anymore + High duty gaskets (tested with burn tests).
block 4 : works !: tight engine, new Sierra "reman" carb fails (again wtf thoughts). So I have my original non performing 2300 carb, this failing Sierra carb and bought an unaltered but low performing 1997 GL carb (63 sized jets). Intention : Holiday : study Holley carbs and rebuild ideal carb. MYSELF I don't care what it costs because I want to understand/learn which does it for me. Got me setup with all documents, gaskets, cleaning material, ultrasonic cleaner and you name it. To wife : this is an optimization project. THIS time it will not cost a lot, I swear ! Which brings me to ...

I had this BOESCH boat, when I was young this Euopean well known runabout brand, I build a garage for the wreck, so I would have a hobby after marriage . Then I got children which is absolutely great. Then it took me ten years to switch between boating, wrong ... rebuilding and family life... and then my wife asked me : what would you like to do...... that was the first wtf moment. After I eased myself, always being calm, ... I said, I would like to go out boating, hmm quite seriously now you're asking darling. Well, the wife said, buy a new boat. Wtf (again), so I thought hell yeah, let me get a Glastron, now, completely the opposite. But where I had a wreck with a good working engine I now had a good boat without a proper working engine it seemed afterwards ... didn't see that one coming at the time. Like a kid in the Playstore. Now I know.

When I was 12-16 I had this 15HP speedboat, no.... it went fast, never had an issue. I was looking at these rich grey hairy guys going around but in retrospect I know now .... I was boating. Never had a concern on the water, got the babes out/in, damn, it was good. Hell, this is the life of freedom, hassle on the job, get on the water : that's where you get piece of mind. Well, it isn't lately, the kids are even afraid to go out with me. That's simply bad.

I want to get the feeling back,sorry for me blowing off. It gets a bit to me. When I am boating, ANY sound and I get the creeps after all this pain,that is what it is. I spend a lot off time learning this engine, carburetors (and I hope not to do so for drives) and I dig iBoats a lot. This is not about complaining but sharing actually my appreciation for a site like iBoats and its community. I share it because I believe a lot of us sometimes have been in this hole, we can cry about it, but we can also laugh about it sometimes. Well, it is a hobby right. And as long the wife is okay (or NOT), we can take a lot eventually. Right ! "No, I drilled that hole for an extra vacuum measurement .... yes, ... no that's not the reason it's on my work bench for 1.3 years,.... optimization, and yeah that one is more .... Are you searching for problems, is that actually your hobby, my wife said : perhaps that's the flaw." That's a question, ain't it ?!


But, uuhhh, any suggestions about my latest concern in the top section, you're welcome !

Regards,

Martijn

 

[alldodge]

Dieseling is caused by an idle which is to high and an running rich, which you have both going on.

If the PCV is jumping out of the rubber fitting it is either to loose and needs replaced or you have major blow by. Seeing oil it might be blow by, but you did say this is the 4th motor

 

[mnjjansen]

Hi AllDodge, many thanks for your reply. The Dieseling, understood and will change that.
Fourth engine you say..... I had manifolds and base engines cracks leading to 4 rebuilds/reman. The one I have now seemED to do well with no water intrusion, no oil leakage.
Your point about blow by concerns me. Low pressure 30PSI, scratching sound and smoke from PCV vent / carb. sounds perhaps I have a piston ring issue (or something with a valve). I am not in the position now to take it out for the next 3 weeks but when I do right after those 3 weeks I will focus more on the potential blow by issue and be careful. I believe a leak down test is something to do here, else we immediately pull the head or complete engine again. As you know that seems to be my boating life anyhow . If I come to conclusions in the mean time I will post it here. It sucks when there is eventually no solution in a topic.

 

[alldodge]

It sucks when there is eventually no solution in a topic.

Sorry if I missed a question. I read thru everything until you said

Unless you're heavily occupied you might enjoy to read the following, just for laughs

Blow by is easy to see, once engine is heated up, remove the PVC and see if you see oil smoke puffing out. If there is no puffing then something else pushed the PVC out and I must have missed a comment.

Diesel solution is get the rpm down and lean out the fuel a tad.

Don't understand the scratching sound because also said there was noise from the ALT

 

[mnjjansen]

Alldodge, thanks again. What I ment is that I have to back with feedback. So my bad and I totally appreciate any effort you already did. Sometimes posters do not get back to the topic they posted once they did get a solution. So, I take your advice, and come back later when I tested matters. At the moment I am deeply concerned about the oil pressure drop. The carb setting will be easy but the oil drop is another thing

 

[mnjjansen]

Alldodge, the pvc system takes up fumes from the crankcase right. Is the a channel for this through the head? Just for my understanding. Blow by typically about these fumes, right? I need to investigate however (also) if oil is passing over the rings up. How else can oil pressure drop, without external leakage. This might explain the scratching also, perhaps the extra fumes? Would I be able to visually check such an event? Thanks.

 

[alldodge]

The lower oil pressure could be from wear (which normally takes time) or thinning of the oil. Your motor has a fuel pump on the block, and normally if the diaphragm starts to leak it will travel up a clear tube to the carb. If the tube is clogged or it leaks slow enough the fuel will make it into the block and thin the oil. If your burning oil and also leaking fuel you may not see the oil level increase.

Check the oil level, and if good maybe change it to see if pressure comes back up.

the pvc system takes up fumes from the crankcase right

Yes, excess fumes are drawn into the intake manifold and burned during the combustion process by all cylinders. Look at your plugs, if they are black and carbon is starting to pump oil maybe. You can also do a compression test to check health.

 

[mnjjansen]

Hi AllDodge and others. After my holiday I took my boat out twice. Started, oil pressure back at 40 psi. Got it out for couple of hours, stayed the same. I did the oil check nevertheless. Nothing, totally clean and basically no loss of volume. I checked the transparent tube as proposed but this is at least in my case the fuel pump going to the carb as safety feature, nothing wrong there. Perhaps gauge issue or some flogging that got out, not sure. Reset the low idle screw that removed the back firing issue. No serious smoke issues after stop out of carb / valve cover. The metallic sound came from the alternator which got worse second ride (for me recognizing now the source), easily solved by setting belt tension properly. The alternator belt tension got done after the oil pressure came up back, so I don't expect alternator output caused a reading issue on the oil gauge (I say this as I saw the trim gauge seemed to vibrate and not anymore). PCV valve seems to have worn out since the typical clicking sound become much louder then normally, ordered a new one. Seems to be a storm in a glass of water but thanks for the support, better be careful too much considering my aforementioned background story. Thanks AllDodge for your support, sincerely appreciated.

Regards,
Martijn