Yanmar 3YM30 glow plugs

[dagern]

Hi,

Anyone changed the pre-heat glow plugs on a Yanmar 3YM30 before? Did not notice in the summer, but when the temperature dropped to only a couple of degrees celsius and I was about do the last start of the engine for the season, I noticed that one or two glow plugs is not functioning as they should, need replacement. Glow relay passing current to plug harness as it should.

Looks like the glow plugs removal on this engine require a bit of disassembling to clear up the area. Just wanted to check if anyone have done it before, and get some good tips.

I guess if you are in warm climate all the time, you never pre-heat the engine. But noticeable when it gets colder here in Norway. Autumn and spring I usually give the engine 5-6 seconds of preheat before starting.


Thanks and regards,
Dag Ragnar

[dagern]

Would appreciate input if any members have done it before

Anyway, will post some pictures and steps I did, when done.

Regards,
Dag Ragnar

[Charlie-Bravo]

Hello Dag, not changed the plugs on a Yanmar, but have on other marine diesel engines, apart from accessing them the main issue is not to force them too much, the last thing you want is to snap them ! Go slowly, and if they seem very tight, start the engine to warm them up, then have another go. If still stuck allow engine to cool, apply a little penetrating oil to them and leave for 24 hours, then have another go with cold engine ..... then warm engine, if still stuck, more oil and more time.  
Carbon can deposit on the ends making them stiff, but slowly unscrewing and re screwing up again and again usually shifts it.
Before putting new plugs in, you need a long reamer or drill of the correct size, or a normal length drill fixed tonto a biro tube,  coat the drill in grease and wind it into the hole by hand, keep pulling it out and remove any carbon and add more grease, the grease is just there to catch the carbon and stop it falling in the bore of the engine. Once the drill goes right through all plug holes you are ready to fit the new plugs, follow the instructions and don't over tighten them.
Replacing the plugs every other year makes it easy, but if they are not replaced for years and years it can be tricky, a snapped plug will require the top of the engine to come apart, so take your time, and all will be well, 2 days to change the plugs is still quicker than a top end of engine removal and getting the snapped bit out.

Will be doing my first Yanmar this winter, so any tips and tricks you find out will be good to hear about.

Good luck

CB

[dagern]

Hi,

Not done the job yet, but it seems pretty straight forward.

New Yanmar parts needed:
3 glow plugs and the rubber valve cover gasket.

Remove air filter and housing, and the 10 bolts for the valve cover. After removing the valve cover all 3 glow plugs can be easily accessed.

From the size of the glow plugs (very small), I think the risk for these being stuck/brake off is very small.

Regards,
Dag Ragnar

[dagern]

Hi,

Short update.

Glow plugs where easy to remove, not stuck at all. Replaced all 3 following my plan in the last post.


Also removed and cleaned the heat exchanger. After 9 seasons it was very clean, and it was not necessary to clean at all. To remove the heat exchanger I pushed the dynamo out of the way (upwards), removed the exhaust elbow, and the front and back plate of the head exchanger. Gave it some careful knocks with a wooden piece from the front, and pulled it out from from underneath the exhaust elbow. Parts needed: 4 o-rings and the exhaust elbow gasket.

Regards,
Dag Ragnar

[Charlie-Bravo]

Good to hear the plugs didn't fight, and came out easy.
 Pulled our heat exchanger last September, and it was clean but a bit corroded on the seal face to the exhaust elbow, the elbow was weeping ...... so replaced with a new one whilst things were apart, I hear they last about 4 seasons, but I guess may last longer depending on use, worth a close look at and replace if in doubt, probably better to replace before it fails, then it won't spoil a trip out at sea.
Happy spannering 
CB

[dagern]

Hi,

I did a close examination of the exhaust elbow, very little carbon-buildup after 8 seasons. The Yanmar engines have a very clean combustion it looks like. No signs of weakness after 8 seasons, but I guess the expected lifetime of my exhaust elbow is running out. I will probably change it next season for maintenance reasons.

Getting closer to sailing season here in Norway these days. Looking forward to it every day!

Regards, Dag Ragnar