Volvo SX 4.3 overheating and oil film???

[96 Wellcraft]

When I bought my used boat, 96 Wellcraft 21 Excel SX, the dealer was concerned about the low engine tempature, around 120. We did the test drive on the lake for 30 minutes, no heat. They tested it on muffs in the shop, still no heat. The dealer changed the thermostat and did a full tune up with plugs, wires ,rotor and cap. He told us to watch the gauge and never run it over 180.

Fast forward the first 2 times we took the boat out I never saw a temp over 120. The 3rd trip out we pulled a tube and my friend drove the boat at WOT for about an hour. I checked the gauge it read 150 or so. The last time out I ran the boat aground on a rock and bent the prop a little. Then later same trip found a mud pit for about 100 feet. I was able to trim up quickly and didn't get stuck, but the engine bogged down for about 5 minutes. Once I found deep water the engine was sluggish and trailing a stream of brown for half a mile. I got past the bridge we were under and stopped in the channel, pulled the engine all the way out of the water and didn't see any mud or apparent damage to the bottom end. That day the we ran another hour and half without any temps above 150. The last 2 times out the temp stayed at 150-160. Today the temp ran at 180 nearly the entire trip of 3 hours. This was all types of running 25 mph cruising, idling thru coves and sections of 15 minute 3000 rpm 38 mph running.

What is my danger zone? The gauge doesn't have a redline.

Also today pulling the plug I noticed alot of oil film in the runout. I've always seen the oil film in the bilge, but didn't notice it before in the draining water.

Thanks, these are just a few of the many questions for a new boater, who believes in knowing AMAP and being very DIY for my sports.

 

[Don S]

Re: Volvo SX 4.3 overheating and oil film???

ANYTIME your temp changes a large amount, you have a problem.
At this point, I would suggest you replace the impeller, check the thermostat, ,manifolds and risers, block, and everything that sees cooling water for mud. Flush everything, put it all back together and do a test run. Then use one of those temp guns and verify the actual temp of the engine and manifolds, risers etc. to make sure what the temps actually are.