Yanmar 3HM35 - stuck precombustion chambers

[SSAsailor]

I'm removing and replacing injectors on a Yanmar 3HM35F. First injector and precombustion chamber came out without much difficulty. On the second and third injectors, the heat shield above the precombustion chamber seem to be fully stuck.
I'm using a metal pick. I've tried boshield to loosen things up. I've also pounded on the top of the heat shield with a brass drift and hammer to try and break things loose (and tried those steps alternately). So far, no movement on the 2nd and 3rd precombustion chambers.
I also tried reinstalling the injectors with the retainer bolts only hand tight, and turned the engine over, with the fuel lines removed, hoping that would break things free.
New ideas please......

[SSAsailor]

I'll add that this is the same setup in 2gm and 3gm, so any experience with the same problem there would be great!

[Manateeman]

Don’t flog my manatee crew but they do have some experience with Yanmar diesels. They take the “easy way” out by pulling off the head, taking it to a shop to have a full valve job done and a new stainless steel exhaust mixer. When I’m not looking, a rebuild on the injector pump, new lift pump, and they rebuild the water pump">raw water pump too. If the old injector parts are in spec, they preserve them wet and keep a full extra gasket set and copper washers in a box.
I get the bank card back and a bottle of “no more tears” baby shampoo, an empty can of engine paint and a huge bill for delivered pizza and beer.
Happy trails to you.
Mark and his manatee crew.

[Compass790]

Originally Posted by SSAsailor

I'll add that this is the same setup in 2gm and 3gm, so any experience with the same problem there would be great!

First off a good soaking with ATF/diesel mix may help


You can try heating the head up if you have access to any heating equipment.
Or freezing spray on the pre-com chamber.
Or if you are going to replace them you can just weld on them being careful not to weld on the head & they will shrink after weld cools.
Sometimes they can be a real bstd to get out.
You should read Wotnames story about his injector removal battle!

Good luck

[j.g.evans]

My 3GM30 will run on one cylinder. Try running yours on the cylinder you have freed. Put a towel over the remaining 2 to catch the parts that will hopefully blow out with faster turn over.