Perkins 4-108 Smoking enigma

[Connemara]

Originally Posted by avazquez

Also I would say the smoke is more white in color......

Ah... then you've just elected a Pope.


Sorry, I have no constructive thoughts. But then I rarely do.

Connemara

[Alan Wheeler]

Hmmmm, I suspect someone may have thrown the themostat over the shoulder when the engine was put back together, or you have a faulty one. Which ever, the water maybe flowing through to fast and if you have an efficient heat exhanger, it is cooling the engine too well. It can go both ways with thermostats removed, the engine can run too cool or it can over heat. It just depends on things not worth going into here.
If the stat is there, you need to test it. Get a temp gauge and place it in water and start heating. It should open at the temp stamped on the Stat. You could do the same with your temp gauge on th engine. Put the sender in the hot water and see if the temp gauge says the same temp as your test gauge in the hot water.

[Jesse Holden]

My 4108 tends to smoke when cold. And somewhat moreso without a load. It will soot up the lube oil in a matter of hours too unless operated above 170 degrees farenheit. These are under stressed, tough and reliable engines with a proven reputation. They are a bit noisy(some say like a trash can rolling down a fire escape) and they are old school to the core. But most of us who have them, love them. Jesse

[avazquez]

Wow...this is great...thanks to all for the excellent response...

I spoke to the previous owner and he did not replace the thermostat with a new one but the instrument panel is new.

I already ordered the thermostat and will replace it. In my engine it is very easy to replace....I believe it is a later version engine. If that doesn't work then I will check the temperature sender to make sure it is accurate. Then I guess I will continue in the cooling system etc.....

[Prflyer1]

Originally Posted by avazquez

I have a Perkins 4-108 on my Beneteau 456. The engine was overhauled by the previous owner. New pistons, liners, rebuilt, fuel pump etc etc.

The engine smokes upon startup with gray smoke. When in gear and running at crusing speed the smoke goes away and the engine runs fine. The temperature barely reaches 180F It usually stays aroung 160 to 170F during cruising which is around 2200 to 2400 RPM. As soon as you put the engine in neutral and it goes to lower rpms it begins to smoke gray again. Actually if you accelerate in neutral it still smokes but if it is in gear it stops smoking as soon as you accelerate.

I already took the injectors to have them checked and cleaned...reinstalled them and no change.

Replaced all diesel fuel lines and filters with a new Racor.

Cleaned fuel tank and filled it with fresh clean diesel.

Checked the timing of the fuel pump.

Still smoking

Any suggestions would be apreciated

I have a Beneteau 38 with the 4 -108 and it has less than 10 hours after rebuilt, and it does exactly as you describe, I was told it was normal but to clean old diesel out, but as your experience has told you it stays the same..... , keeping an eye on suggestions.

Dan

[avazquez]

I am in Puerto Rico too.......Maybe the same person did the overhaul to your engine or maybe the pumps were sent to the same place ........I sent you an e-mail with my cell phone please give me a call....maybe we can figure this one out.....

[Alan Wheeler]

Guy's don't panic. It is a 4-108. This is normal operation for these engines. They are not a modern day desing. They will outlast most all modern day designed engines, but they will not perform like the modern design engines do.

[Benny]

White smoke could mean anti freeze/water mixture is getting into the cylinders and it is vapourized at combustion and expelled with the exhaust as white smoke. This may only be at start up until the thermostat opens up and relieves the internal pressure in the cooling system and the smoke stops. Are you losing any coolant and does the exhaust have an anti-freeze smell to it?

[avazquez]

Ok....This weekend I replaced the thermostat with an original Perkins thermostat. The one that I took out apparently was either bad or a lower temperature thermostat. It had a thinner spring.The result is that upon startup the engine still smokes but reaches 180 degrees farenheit much faster and stops smoking. I would say 95% better. Of course if you throtle the engine suddenly it smokes and then goes away.With the previous thermostat the engine would stay at 140-150 and smoke white on idle, a lot. I guess now I will test it like that for a while. Lets see what happens under load.

[hellosailor]

The change from 140-150 to 180 also means you almost definitely had a raw salt water (140) thermostat and now you have a fresh/closed water thermostat (180).

I'm guessing that's only half of the picture though, because an engine should be able to run with a 140 thermostat without undue smoking. Could be running too rich (injector timing or injectors?) or sucking some oil during loads?

[Maddog]

Be sure to let us know. I belive I said earlier that mine is over proped. I start getting a little white smoke at 1600 rpms then black at 1800. I cruise at 1500 just before any smoke starts. Then pushes me along at 6 knts. I need a new prop this year. However my temp never goes above 180.

[avazquez]

Before replacing the thermostat I was cruising at 2000 RPM's...smoke free at 180F. I never had any problems cruising or overheating....the only problem I've had with my engine is/was the smoke at idle. But my engine can go up to 2500 rpm without smoking too badly.

[avazquez]

Engine still smokes when temperature is below 170-180. Even at 180 smokes a little bit although not as bad as before. I am now watching the coolant level and I believe it is consuming some coolant..............What does that mean???

[hellosailor]

If you were lucky, it would mean a coolant leak from a hose fitting. But combined with white smoke, it would mean a head gasket failing, or some other way that coolant was being sucked into the cylinders.

An easy way to test this would be to send out an oil sample for analysis (look on the web or at a local shop that sells oil, or a local engine shop) for about $20. You'll find out in a week or so if there is coolant contamination in the oil, that would confirm a likely head gasket problem--which needs immediate attention to prevent more costly damage.

[Alan Wheeler]

When you say

I believe it is consuming some coolant..

How much??? Is there a overflow tank the coolant can go to when the engine is hot? and can the coolant be sucked back in whent he engine cools???

Normaly, if you have a head gasket failure and in a place that affects coolant, you would have a pressureisation of the coolant system and it would blow the coolant out. If you have coolant weaping past a gasket and into the oil, you would most likly have it in the cylinder, in which case, that cyclinder would not fire up. A single drop of water can be enough to stop a cyclinder from firing when cold and it would be very obviousely running ruff till the cylinder got hot enough to fire.
As I think I said somewhere above, these engines smoke. Don't expect it to be clean and cleatr like a late model computer controlled diesel.
If it is the head, You could do one very simple try. It may or may not work, but worth a try. These engines are all solid cast. So the heads very rarely warp. But it is possible that the head is not tight for some reason. Remove the tappet cover and crak loose all the head bolts. Then re-torque them back down to the correct tension and in the correct sequance. DO NOT remove or even disturb the head. Just loosen and retighten the bolts. The gasket may be well sealed and you don't want to break that seal, or it will mean a new headgasket.