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Overheating mystery on 1996 Tiara

bdolnik

Member
"Lot's of overheating topi

"Lot's of overheating topics, I've spent almost the whole day reading through them so think I have a better handle on how to proceed. I wanted to document on here what has happened already and what I plan to do, along with updates on the outcome. Hopefully someone will take pity on me and follow along with suggestions


I just moved from a 30' sailboat to a Tiara 3100. It's a 1996 with Crusader 454XL's. The boat was at a broker for well over a year, and was under contract a month or so ago when we first looked at it. The buyer ended up pulling out of the deal after the starboard engine overheated on the sea-trial. The broker replaced impellers and risers on both engines after that.

I had an engine survey done along with the hull survey. The engine survey checked out good with compression tests in the 140-145 range across all cylinders on both engines. The oil analysis also came back normal. The engines run up to about 4400 WOT. Based on this info we purchased the boat on Saturday.

I decided to drive the boat home, via the Intercoastal Waterway (Florida) about 70 miles. About 2 hours into it the engine rpms dropped to idle and the check engine light came on. At this point the temp gauges were reading about 170-175 on both engines and the overheat light on the dash was NOT on. We idled for just a little bit, watching the temp gauge and it stayed in that 170 range. I tried to throttle back up, and again the rpm limit kicked back in.

We anchored and lifted the hatch to see if anything was visibly wrong. I couldn't see anything. Took a swim to cool off, and decided to idle to a marina if possible to have a mechanic check. While idling temps still seemed fine so decided to try and throttle up again. This time we were able to increase to cruise at 3100rpm, and made it the rest of the way home without incident.

Yesterday (Sunday) I took the family out on a very short cruise, just 10 minutes or so of running to an island near us. We anchored and swam for a couple hours. On the way back the starboard temp gauge started acting erratic. It would swing wildly back and forth and then peg at max temp. No warning lights or rpm limiter this time, but I idled back to the slip anyway just to be safe.

I'm going to go by Lowes tonight and get a temp gun and check the temps against the gauge. I had asked the surveyor if he did this and he said he had (I was not present for the engine survey but was present for the hull survey).

Also on the first couple of hours of our trip home Saturday I heard what I thought was belt squealing so I'm also going to check that.

I found some documentation on the boat that described a similar problem in 2006. The work order mentioned the throttle limiter kicking in at 1800rpms, and that they replaced impellers and risers on both engines.

So it seems now this has happened a couple times in a couple years and the 'fix' has always been to replace risers and what-not. I'm hoping with the help of this forum I can finally get to the bottom of the problem.

Thanks,
Bryan"
 
"Seems like the fix has only b

"Seems like the fix has only been temporary; your plan sounds like it has the potential to provide a much longer term solution.

the IR Gun will be a great start. Make sure you take good notes to get a quality baseline.

If I had to guess, I'd venture that you have a harness issue (wiring). The temp sensors for the gauge and the ECU are different. Only the ECU sensor turns on the warning light. Being as both occur sporadically and independently, its probably not a true overheat issue.

I'd also keep an eye on the coolant in the overflow bottle. If its stable (cold and hot levels are repeatable) that another good indicator.

The only other item that comes to mind, for now, would be a thorough inspection of the harness, especially around the sensor connectors and the ECU. A wiggle test of the entire harness may also bear some fruit."
 
"Here's what I found when

"Here's what I found when I checked the starboard engine this evening. It's so loose I can pretty much slip it around by hand.

289153.jpg
Water Pump
 
"the belt is worn out - see ho

"the belt is worn out - see how deep it sits in the pulleys? The outer edge of the belt should be close to flush with the pulleys. you'll see when you get the new ones.

See that rusty ridge around the outside of the pump pulley? And the black dust trail on the stringer? Bet there's dust on the bilge under the belts, too. Don't forget the flats on the outer edge of the V of the belt. All bad signs - from excess belt wear.

Would be a good idea to get a rotary tool and remove the heavy rust from the pulleys V. Scotch-brite pads work ok. That rust is treating the belt like a belt sander. the face of the pulley should be as smooth as the flat, shiny painted surfaces when you are done. If you don't remove the rust, make sure you have plenty of spare belts. and check the other engine's pulleys, too."
 
"Thanks for all the comments m

"Thanks for all the comments makomark. Is there something I should put on the pulleys to slow the rust after I scotchpad them? I assume a lubricant would not be correct, is paint the only thing I should use?"
 
"Good point on dealing with th

"Good point on dealing with the pulley rust, but I'd say the RW pulley needs to be new. After an hour of sanding/scotch brite, etc, you will still have pits. Also, check to see if the pump seal is slinging salt water around.
I'm going thru a similar exercise with the alternator pulleys."
 
"I've found the depression

"I've found the depressions are serviceable, its those rough high spots that eat into the belts. Good call on the seal dripping, Dave.

If you can find and afford them, new ones are the fastest fix. Yes, paint is the economical covering....I think powder coating would be better but last time I checked, you could get another pulley for what the coating cost."
 
I went to change the belts on

I went to change the belts on the starboard engine last night and found the replacements I had were not correct (these were NAPA belts the broker's service people put together for me as a 'cruise kit'). So I just went ahead and tightened it up. I ran the engines at idle and the gauge is still jumping all over the place. I'm going to swap the port and starboard gauges tonight and see if it's the gauge or the sensor.

I played around with the temp gun I bought at Lowes but not really sure what I'm doing with it yet. There's a post on here somewhere that the person wrote the temps on a motor diagram so I'll probably start there. Should I be pointing it at the hoses or the metal parts?

I also ordered crusader belts from marineparts.com today.
 
"Good plan overall. Shoot the

"Good plan overall. Shoot the metal parts, although the hoses are black (good for IR), they are also rather insulative. The single most critical measurement is the thermostat housing at cruise power; should be 165 to 170 deg."
 
"I swapped the temp gauges las

"I swapped the temp gauges last night and the problem followed the gauge, so that's a relief. I'll order a new one today. So what's left is to measure the thermostat housing at cruise and then replace the belts."
 
I'd get the belts right be

I'd get the belts right before taking any more measurements. Last thing you want to do is established a flawed baseline
 
"OK I've got a similar pro

"OK I've got a similar problem. No overheat problem, engine runs a 160 on the money, but I do have a belt squeal problem on the raw water pump. Cleaned pulleys and put on new belts. Still squeals. Took the pump off and there are 3 small holes underneath behind the pully on the shaft housing, Sherwood E35 pump. I gave a shot of WD40 in the holes, put the pump back on and no more squeal, for a while. After about 30 minutes of running, back to squealing. Not real loud but constant. I though about changing the impeller but it seems to be the shaft that is actually making the noise, even though it doesn't leak a drop. Impeller kit is about $30 but the whole rebuild kit is over $100. It has the shaft seals and a few other seals in it. Should I go for the whole rebuild or just replace the impeller and clean up the shaft seal? Never been in the RWP before and looking for a few ideas. And should not use NAPA belts? And if not what is a good brand? Thanks!!"
 
"Concur - you'll need new

"Concur - you'll need new bearings - lots of times, they are available thru alternator shops.

If you don't know the history on the pump, the whole kit is a good idea. The seals are R&R, no cleanup to do.

You'll need a good set of snap ring pliers and probably access to a hydraulic press, too.

Napa belts are functional."
 
"No thanks Mark, I already hav

"No thanks Mark, I already have them!
ps Got your e-mail. Sounds like a good deal!"
 
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