Trojan Boat Forum

When I purchased my '87 F32 last year there was a 35-40 degree difference between the two Crusader 270/350 engines. The port read higher. The starboard idled at 150 and ran at 185. The boat has closed cooling. By the way there are only 1050 hours on these original engines, the former owner is an engineer and immaculately maintained her. She had been sitting for 3 or 4 years with very little use. During survey I asked the former owner about the difference and he explained that the port sensor was changed years ago and ever since then the readings were like that (both upper and lower helm gauges read the same results).

Gradually both engine temperatures started to rise. During the winter, I would start the engines every Sunday morning and tied to the slip, engage the transmissions at idle, and run up to "her" normal temps. One day the starboard temp alarm went off. I shut every thing down and started checking things out. I first went for hoses, then raw water pumps. I replaced the raw water impellers, but noticed during the process that there had been excessive seepage form the weep holes beneath the seals. I put things back to together and didn’t get any temperature improvement. Since the seals were bad, I replaced the pumps. I think those were original pumps. I was quite surprised to notice that the impeller cavity on the old pumps had worn almost 3/16” larger by the years of use! So I really thought the new pumps would lick the problem – no such luck.

I also replaced both temperature sensors. Even though the starboard temperature alarm kept coming on the port one never did – but curiously the temperature difference was still there.

So I dug deeper and found the risers were 11 years old! I replaced them – they were so plugged with rust, I couldn’t see how water moved thru them at all – and had the heat exchangers serviced. Guess what problem solved – on the starboard side. The port still is running hot – even hotter. At the slip she idles up to 165, underway at 1500 rpm up to 185 and at 2500 up to 240. But no alarm!

While running I had one of my contributing mechanics (that means I buy beer and supper at Outback) shoot temps with a laser/IR gun. And believe it or not, no matter where we shot, there was never any more than a 2 or 3 degree difference in the readings between the engines, cooling or exhaust component. At the temperature sensor the starboard reading is nearly the same as the helm gauges but the port shows that damn 35-40 degree difference.

Today I’m going to pull out the alarm sensor and heat it up with a torch and see if the alarm works. I expect that it does and that I’m not over heating at all. But what would cause both helm gauges to read unusually high? Can they be calibrated? Could the condition of the signal wire be a part of the mystery? It looks fine.

I’m out of ideas and I’m counting on most of you to be smarter than I!

Thanks in advance!

Mel Spruill
‘87 F32
Old Point Comfort Marina on the Chesapeake Bay

Molly, what I wouild do is hook up a remote temperature gauge to the suspect engine. Disconnect ALL the existing wiring to the engine, which should only be one wire to the temp sensor and hook up another gauge, right there and monitor it right at the engine. Doing this will ensure that you are or are not running at the proper temp. Once you are sure of that , you can either troubleshoot the wiring or the engine problem.

Have you checked the impeller for your raw water pump? That can be a cause of what you are describing.

Do the senders match the gages ? Are the senders made for duel gages ?
there is a diffrence . make sure you have good grounds for the gages

"The port sensor was changed years ago and ever since then the readings were like that .." If that is true, there is where I'd start. Sounds like the wrong sending unit.

Agitator wrote:"The port sensor was changed years ago and ever since then the readings were like that .." If that is true, there is where I'd start. Sounds like the wrong sending unit.

I agree ! I asume you have uper and lower helms ?

Mel , I just realized your the Trojan boater near me . I would be more then happy to look at it Give me a call I sent you my number to your email .

Your could swap sender from one engine to the other and see what happens

I think the problem might be that his dog pooped on the dock and he didn't clean it up!!

Roy .... hahaha you need another cup of coffee

Roy,
That really was a worthless post.

how about changing the thermostats? that finally cured my onan problems. the originals had not been changed since it was installed in 1976! after my mechanic friend and i did that, we did a complete flush with marykate on&off to get the rest of the crud out.

For those interested, here's an update.

It turns out that the port engine really is overheating. And there isn't a problem with either the running or alarm temperature sensors. I found out that the difference in reading between the two engines was caused by differing sensor types. It turns out that there are sensors for single helms and for double helms. I had one on one engine and another on the other.

Having seen posts about air in the outlet side of the raw water pumps. I next took off the oil cooler and cleaned it (acid dipped and so on) and put it back on. Then I replaced the oil cooler to heat exchanger hose with a clear piece of tubing. Guess what! At idle I had 70% to 75% water - the rest was air! And at 1200 rpm it was 50% - 50%! And!! I noticed these lima bean sized gobules of red stuff going past. UhOh! Transmission Fluid. So I got a new cooler. But I still had air. Not as much but I still had high temps and steam in the exhaust.

So I contiued going backwards all the way to the seacock. I took the hose off, opened the valve and had "good" flow. But what's good? So not knowing, I put the strainer hose into a 5 gallon bucket and filled it with a garden hose while running the engine. It actuall took two hoses to keep up with the pump at 1200 rpm. But guess what! Normal temps, no air and NO EXHAUST STEAM. It turns out that the seacock is full of who knows what. Diving didn't turn up anything on or in the strainer. Snaking it didn't work, backflushing didn't work so I'm hauling this weekend and checkin all of them, actually all 5 of them. These were Groco SV series valves. They have packings and they're 22 years old. By the way Patrick at Groco is a great source of seacock knowledge and they still have some packings left to sell.

My take from now on about exhaust steam, in split cooling systems, is that if there's enough flow there isn't time for steam to be created. I know the other variables play into this but I had steam with 78 degree sea water and 95 degree air. If there's steam, there's a restriction. Those raw water pumps can really move some water. Lord knows how much at WOT.

Paul, I'm hauling at Deep Creek Landing across near the Warwick Yacht Club. I want to call you to talk about metal coatings or paint. I used Barnicle Block last year and was almost useless. I think you mentioned something on the phone the other day

Mel Spruill
‘87 F32
Old Point Comfort Marina on the Chesapeake Bay

Mel propspeed or prop kote

http://www.propspeedusa.com/

http://www.pettitpaint.com/catalog_brow ... ictNbr=169

propspeed is the best .

When you pull the boat, check the strainers to see if the openings have been reducer in size by bottom paint. Multible coats of paint can drasticly reduce the amount of water that will flow through the strainer fins. The strainer should be bronze and the paint should chip off it fairly easily. Once you have it clear of paint, you should give it a fresh coat of bottom paint to keep the baricals from restricting the flow latter.

Mel feel free to call (I sent the number in a PM in case you lost it )