New head gasket bad?

[Jim Phillip]

Just finished putting in a new head gasket. Warmed it up and retorqued without anything amiss. Ran it for about 15, was going to do the hour and last retorque, and it overheated. No water in the oil, no noticeable leaks, and no bubbles in the overflow. Flushed the radiator and and restarted, got hot in about 20 minutes of running at 2000RPMs. The radiator water is moving around but not bubbling over. The radiator is about 3 years old and I had the head and valves done by a shop and they assured me it was straight. I assume I should just pull the head again? I checked the block really carefully and its straight and no visual cracks. Getting pretty frustrated with the damn thing!

 

[olddavid]

Did you remove the thermostat? Could it have been reinstalled backwards? I believe some head gaskets can be put on backwards or upside down and accidentally block cooling passages.

 

[Jim Phillip]

Sorry, should have been more specific. 2 cyl. YM240D. They don't have thermostats. The head gasket can go on wrong, but only in one way and it would be really obvious that the head doesn't have passages under the head gasket holes.

 

[winston-HT]

What were symptoms before head gasket change? After head g gasket change, did light come on? Coolant boiling over?

 

[bmaverick]

Sorry, should have been more specific. 2 cyl. YM240D. They don't have thermostats. The head gasket can go on wrong, but only in one way and it would be really obvious that the head doesn't have passages under the head gasket holes.

What engine oil are you running. We are in a heat wave right now. SAE 30W should be the oil to use in average temps over 86F.

Do NOT use 15W40 in these Yanmar engines, the heat takes much longer to dissipate in these diesel engines. It's the reason why the head gaskets go and the heads swell, causing issues.

Deere SCUT & CUT with a slew of Yanmar engines.

 

[kencombs]

Just finished putting in a new head gasket. Warmed it up and retorqued without anything amiss. Ran it for about 15, was going to do the hour and last retorque, and it overheated. No water in the oil, no noticeable leaks, and no bubbles in the overflow. Flushed the radiator and and restarted, got hot in about 20 minutes of running at 2000RPMs. The radiator water is moving around but not bubbling over. The radiator is about 3 years old and I had the head and valves done by a shop and they assured me it was straight. I assume I should just pull the head again? I checked the block really carefully and its straight and no visual cracks. Getting pretty frustrated with the damn thing!

What was the actual temp of the water? Boiling or not? I don't see any symptoms noted that would indicate a gasket issue. Maybe water pump if the water isn't circulating. Small diesels seem to be really sensitive to airflow too, and often gather dust/pollen/stuff on the radiator fins.

My little JD with a Yanmar needs the fins cleaned often when mowing in dry/dusty conditions. Like every 3-4 hours of use.