Suzuki DF150 overheating

C

Captains Cat

New member
The new owner of THATAWAY is in town preparing to cruise for a couple of weeks on the Chesapeake. Launched at the marina last week and the port engine overheated after about 20 minutes. He had just replaced both impellers and the engines pumped water well. We took out the thermostat and he made it over to my pier (5 miles or so with no problem).

Ordered two thermostats from Browns Point (great overnight shipping) and installed one in the engine. Ran it alongside the pier with no overheating problem. Got underway today and again it overheated. Came back in and took the thermostat out again. He left a couple of hours ago and will return tonight.

In the meantime, I'm trying to figure it out. There are two temp sensors but if one were bad, the removed thermostat would make no difference. I'm thinking salt buildup in the block enough so that an open thermostat won't provide enough cooling but a removed one will.

Any ideas?

Charlie
 
How much salt water did you run the boat in? When I ran the boat at least 80% was in brackish, and it was always run in fresh water for 10 to 15 minutes after each run. Certainly salt build up is a possibility. How were the impellers when he changed them? Any possibility that an impeller blade might have come loose? I would also check the engine with an IR thermometer--this may localize where any overheating might be. Possible bad sensor--but that would be unusual. Beyond that I don't have any ideas right now.
 
I dont have a shop manual to explain testing sensors and whether it throws a code when scanned


Was the impeller only part changed or the entire unit?
 
He used the water pump rebuild kit. And used the service manual and D Rays YouTube video. No blades missing from either of the old ones.

On the way back, he lost RPMs on that engine but has not checked or changed fuel filters. Does not overheat with tstat out. We'll use salt away in the morning. And check racors and the two under the hood.

Charlie
 
I've given him the salt away and the two hose rig that I made up so he could either do both engines at once or one engine on the two flush ports. He opted just to leave the tstat out. He also had problems starting that engine. Turns out he didn't replace the racors. After doing that on both engines, he still had problems on the port engine so I told him to fill the LP filter under the cowl with gas and the racor. Neither one had filled as he cranked it. The stbd engine did fine.

Must have been air bound or something. It sucked gas immediately and he got underway. They are up in the Bay now and both Suzukis have been running fine, he says.

They bought a Ford F-450 2008 King Ranch crew cab truck, 6.4 L diesel to pull it with, his wife isn't doing real well so I think think they will stay on the bay and Potomac for a month or so and head back to WA.

Charlie
 
Captains Cat":1o2qon0i said:
I've given him the salt away and the two hose rig that I made up so he could either do both engines at once or one engine on the two flush ports. He opted just to leave the tstat out. He also had problems starting that engine. Turns out he didn't replace the racors. After doing that on both engines, he still had problems on the port engine so I told him to fill the LP filter under the cowl with gas and the racor. Neither one had filled as he cranked it. The stbd engine did fine.

Must have been air bound or something. It sucked gas immediately and he got underway. They are up in the Bay now and both Suzukis have been running fine, he says.

They bought a Ford F-450 2008 King Ranch crew cab truck, 6.4 L diesel to pull it with, his wife isn't doing real well so I think think they will stay on the bay and Potomac for a month or so and head back to WA.

Charlie
Click to expand...
I assume you told him that if he runs for a long period of time without the t-stat, he could cause problems down the line - e.g. if the engine never gets to the proper operating temperature, a few problems can be created - excessive carbon build up, excessive fuel blow by since the piston-ring cylinder clearance is effected by thermal expansion, moisture collection in the oil system, etc. While some run for a long time without a t-stat, it probably increases wear and tear on the engines.
 
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