Steaming again...

Sounds like good progress. Hopefully that was it.

I have had good success with BB, hope it works for you.

I am reviving an old thread of mine, but thought providing closure would help provide a possible solution to someone with a similar problem. To summarize, I was having a steaming/white smoke issue during cruise and engine coolant temp was reaching its upper temp limit at WOT.

- I serviced the injectors, which did resolve the stinky fuel smell and slight diesel slick at start up. Still had steam though.
- I removed/cleaned the exchanger (no blockages) and flushed engine with Barnacle buster. No change in temperature and temp was 200 degree at WOT.
- Added a Volvo Penta expansion tank to increase coolant capacity and better monitor coolant. No difference.
- Double checked the through hull, rebuilt the Perko sea strainer, and inspected raw water hoses for any blockages. All good.
- Hull and running gear were clean.
- Replaced impeller.

The Volvo, cast iron high rise injection elbow was only three years old and I did open the service ports to clean out the carbon. I assumed all was good. I revisited the elbow and removed it for full inspection. Water flow was definitely being restricted--it was nasty inside even after cleaning via the inspection ports.

I reached out to National Marine Exhaust and had a high rise, stainless steel injection elbow fabricated to include fiberglass wrap. I installed the elbow and was pleased to see ZERO steam and coolant temps at around 170 or a little over after 10 minutes WOT in warm gulf waters.

I could kick myself for assuming the elbow was fine.

Way to go there, Inspector! Another assumption people seem to want to make is that the impeller is ok just by a sight inspection of the thing when the cover plate is removed. I gentleman on the boatdiesel.com forum went through hell trying to figure out the cause of the very same symptom you experienced, ok temps at low RPM and high temp and steam at high RPM. He finally pulled the impeller (having "inspected" it before) and found that by pushing on it the central core came out. He also discovered that the after-market, non-Johnson impeller was actually slightly larger in diameter that the impeller it was reputed to replace. He went back to the twice-as-expensive Johnson part ans swore to never make that mistake again.

Vashon_Trawler said:

I reached out to National Marine Exhaust and had a high rise, stainless steel injection elbow fabricated to include fiberglass wrap.

Click to expand...

I have also used National Marine Exhaust for a custom elbow and found their knowledge, service and product first rate!