My 1986 3GM30F was overheating so I've been through all the checks. The coolant was 1 qt low and that has temporarily solved the overheating. My Yanmar mechanic thinks the head gasket may be blown leading to the low coolant/steam using the following logic: 1. White steam/smoke from exhaust under load - 3000rpm 2. Low coolant. 3. Noticed some bubbles in the coolant when running. 4. Heat gun showed mixing elbow at 85 degrees and engine temp was 185. So still running hot. 5. Have not pulled heat exchanger yet. Dowels passed through no visible build-up. 6. Placed compression test on radiator cap and was getting pressure. This is the first time I have heard/seen this test. Anyone want to take provide some thoughts on the compression test and blown head gasket? Any other thoughts? Thank you, Tom
3GM30F white smoke/steam
- Thread starter Tom-in-Annapolis
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Bad news
My first assesment is a blown head gasket. 185F is warm but ok. Bubbles in the coolant is very bad. What pressure were you getting at the cap? Pat McCartin Inland Marine Diesel Buford, Ga imd_ga@hotmail.com
My first assesment is a blown head gasket. 185F is warm but ok. Bubbles in the coolant is very bad. What pressure were you getting at the cap? Pat McCartin Inland Marine Diesel Buford, Ga imd_ga@hotmail.com
Some observations...
...from a non-diesel, non-mechanic. 1. 3000rpm is a bit high for that engine under load. 2. 85 degs at elbow and 185 degs at engine may be a t-stat. 3. Raw water impeller OK? Good Luck!
...from a non-diesel, non-mechanic. 1. 3000rpm is a bit high for that engine under load. 2. 85 degs at elbow and 185 degs at engine may be a t-stat. 3. Raw water impeller OK? Good Luck!
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