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1978 Crusader 454 cooling issue

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bertram31

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I’m new to inboard engine repair, so I will do my best to describe my problem. I have a 1969 Bertram 31’ SF with twin 1978 Crusader 454’s. Engines were rebuilt about 4 years ago and have run fine since I bought the boat 2 years ago. Starboard engine began overheating, 220+. No leaks in cooling system, hoses & clamps OK, no blockages. Changed impeller, backflushed system, no improvement. Disassembled exhaust manifolds/risers, found highly corroded, replaced both on that engine. Replaced thermostat, was a 180, replaced with a 160. No leaks. Gauges read 180-185 at idle. Shot with IR thermometer, read 162. OK, the sender is probably bad. Ran on plane at 2800. Inside riser 160, outside riser 180, thermostat housing 176. Shot IR temp of port engine (old manifolds & risers are probably corroded as well), risers 110-115, thermostat housing 182 (180 thermostat). Water is flowing nicely from transom exhaust, although much more exhaust/steam on starboard side with new components. Why are the new starboard risers running so much hotter than the old ones on the port side, and why is the thermostat housing running hotter than the thermostat rating. Thanks very much.
 
bertram31 said:
Why are the new starboard risers running so much hotter than the old ones on the port side, and why is the thermostat housing running hotter than the thermostat rating. Thanks very much.
Click to expand...

HI, and welcome to the crusader forum. Lots of experts here to help. Simply, the stb engine is likely moving less raw water at cruise than the port engine. Lots of suspects, and we all have our own favorites that we have rooted out over the years. Here is an incomplete list: raw water pump not in great shape, not just the impeller, but the cover (scored) and worn cams are typical. The U cooler is clogged. Very common if over 10 years old. Not usually responsive to water backflushing, either. If over 10 or 12 years old, replace them due to internal corrosion. Younger coolers respond well to acid wash or just open it up with Mapp gas and dig out the old zinc, etc. Leaky RW strainers, usually an O ring sucking air. Collapsed intake rw water hose or coolant pump intake hose. Thermostats should be 160's, and the housing runs at mid to upper 160's at cruise. If not flushed with fresh water regularly, the HE will need rodding out or taken to a marine HE shop for cleaning.

Steam and hot risers are the giveaway for low raw water flow, and flow really can't be "measured" by eye.
 
Dave,
Thanks very much for the response!

HE was cleaned early on. I'll check the RW pump/U cooler. I'll let you know what I find.

What temp should the risers be at cruise? 110-120?

Thanks again!
 
you will be able to keep your hands on most areas of the raw water cooled risers at cruise on a healthy system. 110 to 120 is about right.
 
twin crusaders in a old 31 ft. Bertram ...hmm sounds like one of those vintage Mopies by Bertram ... nice vessel. Before you go cleaning any part of the raw water side and taking things apart, highly recommend you purchase some Rydlime ... Great product and saves you a ton of money and time. You can run it through you engine and it will clean and clear most all deposits and corroision inside the sea water loop without taking a thing apart. We used it recently on a newer 8.1 Crusader and we were able to bring an overheating problem back to "new' parameters immediatley. We did all the normal stuff before hand, impeller change, hose check etc and when they turned up empty, soaked the engine raw water loop and it did the trick fantastico. Fully agree with DiverDave regarding the UCooler. We had a 454 for almost 13 years and the zinc anode did in fact typically clog the water flow to cause high temps. Fortunately that is a simple fix, and even if you have to replace an old unit, its easy and cheap and no mechanic needed so long as you find a replacement part. Usually located on front of engine in easy location. Hope this helps. Check our Rylime thought we got great results and its inexpensive and gets diluted 50/50 with water. good luck ... Allen
 
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