Did overheated Dagenham contribute to broken Valve Guide?

[Keijo Isomaa]

Haven is a 1966 32 with a 590E Dagenham engine. It was essentially rebuilt in 2014 (coolant in oil problem). In 2017 (at 506 hours on rebuilt engine) I had an overheating incident (temp gauge near 240). After that engine smoke was a little more than usual and it had a light ticking sound. Oil analysis showed no abnormal metal levels. Continued to use engine until 588 hours when valves were adjusted which eliminated excess smoke and the ticking sound. Engine ran great.
Recently out for 6 weeks up BC's central coast. On the way back down Johnstone Strait we had a valve guide break (abbreviated version of story). Limped into the only dock around and later got a 50 mile tow to Campbell River where the boat sits now (still 100 miles from home port in Sidney, BC). This happened at 838 engine hours.
I understand this engine is "sensitive to overheating" but I'm not sure what that means. What engine parts (if any) might have been compromised by the overheating? Valves and valve guides? Perhaps the valve guide break is not at all related to the overheating?
Our confidence level in the engine has been seriously eroded. Why would a 5 year old valve guide break? What about the others?
During the six weeks, we were in some very remote locations and we count ourselves very lucky that it happened where it did. Everything is on the table now including re-powering.
Does anyone have anything useful to contribute here?

Thanks,

Keijo Isomaa

[gsholz]

Sorry to hear about your issues and understand your frustration. It is not uncommon for damage from a serious overheat to show up 50-100 hours after the event. There may be other latent damage.

What to do now? At this point the head has to come off (it probably already is off) and checked out in detail. A head rebuild is probably in order. If the cylinders show any scuffing from the overheat, you are looking at a full rebuild again.

What caused the overheat?

[Keijo Isomaa]

Overheat was caused by the alternator belt breaking which in turn hit the plastic hose running from the bottom of the radiator to the overflow bottle which drained the radiator. This happened just before going through Dodd Narrows, just south of Nanaimo. Our mechanic will be at the boat on Wednesday so hopefully we'll have some answers then.

[gsholz]

Have you talked to your insurance? They will not cover the belt (a wear and tear item) but the subsequent damage should be covered.

[Bob Lowe]

Good thought.

[StevenD]

Sounds kinda like the belt that broke stopped turning the raw water pump, which led to the overheat condition. The over flow tank (aka expansion tank) only takes and holds the extra coolant that has expanded due to the normal heating and contracting between running and not.
Of course this is all trivial bs after the fact. Best of luck with the engine.

[Keijo Isomaa]

The overheat was two years (and 300+ engine hours) ago. Insurance addresses only the money issue not the engine issue. I'm considering re-powering and would like some thoughts on an appropriate engine for a 1966 GB32 woodie.

[Chesapeake]

Keijo, PM sent.

[Keijo Isomaa]

Engine damage: broken valve, broken valve guide, bent push rod, damaged piston. Cause: unknown. I will not repair the engine (590E Dagenham) which was rebuilt in 2014. It will be available for parts. Haven will be re-powered with a Cummins 4BT or a 6B.