no start Yanmar

[bljones]

Originally Posted by arvicola-amphibius

Once up and running, it produces plenty of power, and no more black smoke than one would expect at wide open throttle. At 2200 to 2300 rpm it runs smooth with no smoke and pushes my 30 ft boat at near hull speed. After that first reluctant start of the day, it always starts easily enough without resorting to the Aerostart, unless it gets really cold again.
A local Yanmar mechanic reckons that these salt-water cooled engines commonly get corrosion in the exhaust valves, which means removing the head and getting the valves reground etc. But the compressions feel OK - at least I can hardly turn it on the hand crank unless I de-compress the valves. ?

Your compression is low. I know it FEELS OK, but Yanmars are finicky- anything less than 285-ish and it will start....eventually. The easy parts you can likely do yourself.
1. Start with taking off the "bonnet" and checking the valve adjustment.
2. If it's within spec, then check the cylinder head bolt torque. Tighten the bolts in the proper sequence.
3. Pull off the exhaust elbow and clean out the crud.
4. If still hard starting, bring on a mechanic to do a proper wet and dry compression test.

If the numbers prove out low compression, it's time to pull the head and see what is what. Could be valves, (culprit #1) or head gasket (culprit #2), valve stem seals (culprit #3) or it might be time for rings on at least one cylinder (less likely culprit #4).

[arvicola-amphibius]

Thanks all for your advice. And I thought Yanmars were the best! I now know that the best engine I ever had in a boat was a 2 cylinder Bukh. It would hand start and run on anything from jet A1 to tar (almost).

[casey1999]

Originally Posted by arvicola-amphibius

I regularly check that no surplus water is anywhere in the exhaust system.

How do you do that? I was thinking I could drain the water lift muffler if it would help to prolong engine life. I have a 3GMD (30 years old) and after each use I flush with fresh water.
Regards

[arvicola-amphibius]

My boat has a drain tap plumbed into a low point in the exhaust which drains back to the bilge. When I open it I just watch to see if any water flows back to the bilge and it is rarely more than a cupful.
I once went to the trouble on a former boat of fitting a freshwater flush Y valve, but I don't think it made much difference. The zincs still had to be changed every 15 months or so. Yanmars are very corrosion resistant and the steel bit that does rust (the exhaust elbow) gives plenty of warning and is not difficult to replace. If you wanted to spend the money, you ould probably replace it with stainless, but dunno if it would be worth it because stainless can still crack with heat and vibration.

[casey1999]

Originally Posted by arvicola-amphibius

My boat has a drain tap plumbed into a low point in the exhaust which drains back to the bilge. When I open it I just watch to see if any water flows back to the bilge and it is rarely more than a cupful.
I once went to the trouble on a former boat of fitting a freshwater flush Y valve, but I don't think it made much difference. The zincs still had to be changed every 15 months or so. Yanmars are very corrosion resistant and the steel bit that does rust (the exhaust elbow) gives plenty of warning and is not difficult to replace. If you wanted to spend the money, you ould probably replace it with stainless, but dunno if it would be worth it because stainless can still crack with heat and vibration.

And stainless is actually not recommended for exhaust parts as the exhaust and sea water make a corrosive mixture which leads to corrosion. Although my exhaust riser tube (located just before exhasut stern exit) is made of stainless and apparently has lasted many years.

[larrytwo]

Originally Posted by dabnis

One way to find an air leak is to pressurize the whole system like this:
The Diesel Page, Electric Lift Pump and Racor Filter installation
Pump can be mounted right after the tank outlet for testing. I believe some have a "flow through" feature that allows the electric pump to be left in place and used only for bleeding or emergencies if the regular pump fails. If the regular pump's diaphram fails fuel could possibly leak through into the crankcase? If using the electric pump on an ongoing basis it might be a good idea to by-pass the diaphram pump?

Dabnis

I was having some problems with my yanmar gm10. Installed a small flow through fuel pump with it's own switch. works great for bleeding the system.

[arvicola-amphibius]

I am pleased to report that after re-torquing the head and resetting the valve clearances to the book figure, all is well. Everything had got a bit loose (new engine, apparently never had a selling agent's post-delivery service after installation).
I crank it on the decompression lever for about 10 seconds to get the oil circulating, then give it full throttle and throw the decompression lever and it fires right up. Lucky I can reach the throttle from the start panel because as soon as it fires I pull it back to 1200 rpm for the warm up. The thought of it going straight to 3000 rpm from cold is just too much to bear....Though having said that, this is exactly what some diesel aircraft ground power units do every day of their lives and they seem to run very long hours between overhaul.

[Ameridacusa]

Yanmar 3JH3E ...trouble bleeding engine. Question.! ..are there any high pressure blessed points after secondary filter. No fuel or air bubbles on #2 injector 1 and 3 OK.! Engine won't stay running after help from starting either spray! As an ex- Caterpillar Dealer..this Gray toy Yanmar..! Needs a coat of yellow paint.! Help please..my retirement days are getting shorter and I can't leave the dock.!!

[casey1999]

Originally Posted by Ameridacusa

Yanmar 3JH3E ...trouble bleeding engine. Question.! ..are there any high pressure blessed points after secondary filter. No fuel or air bubbles on #2 injector 1 and 3 OK.! Engine won't stay running after help from starting either spray! As an ex- Caterpillar Dealer..this Gray toy Yanmar..! Needs a coat of yellow paint.! Help please..my retirement days are getting shorter and I can't leave the dock.!!

Go here for a manual and instructions how to bleed on Page 27:


Technical specifications of previous models - Yanmar Marine

Here is manual:
http://www.yanmarmarine.com/theme/ya...Manual-ENG.pdf

Looking at the manual, it looks to be similar to my Yanmar 3gmd. You would use the lift pump to get fuel to the fuel filter (engine mounted). Use the bleed screw at the top of this filter to bleed the air (note there is a plastic washer under this bleed screw- replace with new as a crack in it will draw air). Then turn over the engine with starter (with engine stop cable pulled, and sea water seacock closed- so you do not flood the engine) with the line going to the injection pump cracked (at the injection pump) so you can bleed that air. Once bled to the injection pump, you will now crack each line to each injector to bleed the air to those- turning over engine with starter and stop cable pulled, start with the farthest injector and work towards the injection pump to bleed farthest line and working forward.

If you can find someone knowlegeable about boat diesels it will make life easier. Also, verify your lift pump is working- these yanmar pumps can be manually operated by hand even when mounted on engine.

The manual for this engine seems to indicate there is an automatic air bleed system after the fuel filter, so the manual says all you need to do is bleed up to the fuel filter and the auto system should bleed the rest. The question is does you engine have this system and if so, is it working? More reason to get a knowledable Yanmar mech ever if only for an hour or two to show you what is what.

[Ameridacusa]

Casey..! Thanks ever so much for that advise.! Will try again and get a Yanmar expert to look over my shoulder.! Never ever had this much trouble with all my years with Cat engines.!
Best Regards
Dick Rawlings