burnt rubber smell

[tranmkp]

engine runs well - not overheating - 180 degrees - accurate, but the exhaust elbow when running at high speed seems to make the exhaust hose smoke a bit? Should I be concerned? Plenty of water is being discharged. There is no blockage.

[Frosty]

engine runs well - not overheating - 180 degrees - accurate, but the exhaust elbow when running at high speed seems to make the exhaust hose smoke a bit? Should I be concerned? Plenty of water is being discharged. There is no blockage.


Obviously not enough. Check the impellor if you sure there is no blockage.

[mark775]

also, the atomization (shower head) part of the exhaust might be failing. Take the hose off and look.

[alex folen]

The highest temp my diesel ever attained was 155 degrees max, Atomic 5416. Manual says operating temp. 175. Anyway, isn’t a proper hose designed for greater temps then 180? Could be something else heating up on the hose or elbow-recent cleaning, an oil change, beer?

[mark775]

All it takes is for the water not to atomize well, flow along the bottom of the hose, and the top burns. If there is corrosion, it can happen in a heartbeat.

[tranmkp]

180 thermostat - opens - interesting about the atomization. When I pulled the exhaust elbow - it was clean (to the eye) but sooty. I did see a "injector" but it did not occur to me to look more closely. Crap, I just got it all back together...

background - I had the engine repainted - some genius forgot to remove a small rag on the outlet side of the water/exhaust manifold. Short story - when testing - everything ok at cruise rpm 2k when full speed 3800rpm overheat real fast and the NEW exhaust hose began to smoke quite a bit - nore fire mind you but it was smoking. Next day tore it down, removed the cloth obstruction, flushed the system, refilled and off we go - no overheating at all - all the way to 3800rpm, but at the higher (hotter exhaust) rpms, I am getting the burning rubber smell, the smoking is very little actually - wondering if it is just residual from the previous hot outing? The burning/smoking only happened wher the metal to hose contact on the elbow. So, if I remove the injection hose prior to running and it has great flow - it could be moot because of restriction at the injector at the elbow. Ok, so I remove the elbow, attach a water source- what should I be looking for? A shower type of spray or a heavy stream of water.

cheers

[mark775]

A shower. In fact, many more engines have problems at this point because they don´t atomize enough at low RPM. There is a set of holes around the perimeter of the mixing elbow. If the bottom ones are too big, the water just flows at idle rather than ever getting to the top ones and the hose can overheat. If you are just overheating the hose at high RPM and there is not corrosion of the mixing ("atomizing", some call it) area, there is more likey blockage but it seems strange that the engine isn´t over-heating, as well... But do check and see if there are spruce needles, bird feathers, bits of partially corroded metal, RAGS, etc., in this area. Good luck

[Frosty]

Whilst all these reasons are valid causes it has not yet been determined if this is deisel, petrol, turbo, or under load conditions.

Ample water flow is by personal judgment and sticking your head over the side to have a look.

As I understand it,--it is also freshly painted!!!!!!!!

[tranmkp]

Frosty - this is diesel, non turbo and under load. Water flow is good at cruise - have not looked at flank speed because auto pilot complains at that speed - But the engine does not smoke (thru exhaust) white blue or black. The pump is new as is the impeller. I do know the system is clear of debris. I checked and the shower heads exit is flush with the elbow - so, there is no water coverage to the hose at the elbow where the hose fits and is clamped. Metal to rubber, that is what is smoking or at least getting hot. I could get some silicone hose but I really would like to become more familiar as to what is going on.

[Frosty]

If you can put the flat of you hand on it then it is not hot. I am thinking it is just paint smouldering. Run it a while longer.

How many hours has it been running?

[tranmkp]

well, after great tribulation - I tested the water injection/aspirator/annulus whatever its called - sprays like a normal shower -

put it back together - cruise no issues - run it up - elbow get too hot to touch. So, I have to live with it - unless I get an elbow that has a water jacket but who wants to spen 700 bucks...besides - I was hust checking out the prop to see if the engine was not loading - it was not.

[Frosty]

But what is burning? you say a burnt rubber smell?

If the elbow rubber is smelling like its burning then you go to get more water through it. You tested it with what a garden hose? this would supply much more pressure and look to be ok.

What engine is this anyway.

[alex folen]

Yeah, knowing the engine may help. I was told you should be able to touch the engine parts where there is H2O to cool without a 3rd, or 2nd degree burn, anything else you may have a problem? But I have considerable callus on hand.

[tranmkp]

the injector/annulus sprays water at the exit of the elbow ( it is flush, not inside the elbow) - there is no water on the several inches the exhaust hose covers. When the engine had a blockage - that area got REAL hot and caused the hose (just where it mated to the elbow) to smoke - like someone did a burn out in a car. Now everything is fine - however the burnt smell lingers and the elbow does get hot but only at max rpm - This is a displacement hull, I would never red line the engine for anytime.

Engine is a westerbeke w-70 - Hose where the double clamps is the area where the heat is.

http://www.artshot.net/westy.jpg

[Frosty]

I notice you have a dump bucket on there(exhaust silencer) if the rise is too much or pipe too small this can cause back pressure and fight the water pressure so reducing it.

[pogie joe]

I know you said that your not overheating but did you pull that raw water line and check for full flow?:D

[tranmkp]

I guess you mean the line that exits the bottom of the heat exchange. - Yep - besides its a new exchanger. I mean at 3800 rpm you have got a lot of exhaust velocity going on. Ill keep a watch on it.

Frosty - yes back pressure is important - same muffler since 86 I guess. How would I know if it the right size?

[FAST FRED]

If the water going to the exhaust elbow is too hot to touch (over 140F) it is plugging the heat exchanger and other areas with salt from the heat.

FF

[confused]

The burnt rubber smell might be a gasket getting roasted

[tranmkp]

Out sunday for a long run - not so bad now - I expect the time I had blockage and it got so hot - seems even less - Max rpm stayed cool enough - manifold was hot, hot to touch. No burny.

dealing with the prop pitch - rpm issues.