454 XLI overheat

I posted a threat back in April concerning my port engine on our new to us 97 Tiara 2900 open. I had the risers/elbows replaced on both the engines in May. The port engine was heating up hotter/faster than the starboard engine but wouldn't go about 180 at idle. The history was anytime the engine was pushed up above 1000 rpms it would start to get hot (i.e. 210 plus until pulled back.) The mechanic hooked up his computer to it and said that both the motors were about 155 vs. the 175 gauge said at the time (starboard said 160ish). After that I took the boat out and ran it for about 5 minutes and it didn't get above 180. I thought the problem was solved and left it alone. We mostly idle around due to local restrictions so don't get to run it that much. I went out last weekend on a short cruise and as soon as I pushed it up to 3000 rpms it started to get hot again. It got up to 220 and the high temp light came on after several minutes. I would tap on the gauge and it would go to full scale hot. This fueled my thought it was a gauge error. I pulled it back and idled back in. I swapped the gauges on Friday and went out again on Saturday. I pushed the throttles up to 2000 for 1 minute. The gauges were both rock solid at 180. I then pushed the throttles up to 3000. The port engine started indicating hot again and after approx a minute was 210. I pulled the power back to idle. I then ran the boat at 2000 rpms for another 8 minutes. The port temp indicated 200 while at 2000 and the starboard stayed at 180.

I also noticed that the port overfill coolant tank fluctuates between the full/add more fluid lines...i.e. i took it out and it was just above the add more fluid line and when I came back in it was at the full line. The starboard tank is always at full. The coolant on both motors was replaced when the elbows were replaced.

90% of our time is spent idling around. Both of the engine indicate 175 at idle. I do think there was an issue with the port gauge which is now the starboard gauge because it indicated hotter (10 degrees or so) when the panel lights are on and because of when tapping on it would go to full scale hot. The mechanic said when he changed the risers that he thought it was either a gauge or sender issue. I have ruled out the gauge and moving on the sender. However, it doesn't make sense to me that it would be solid at 175 on both engines at idle and then only get hot on the port engine. I would think if it was a sender issue it would be consistent error across the complete spectrum of power settings.

Thoughts/Suggestions? Thanks for the help in advance. I want to try the issue resolved by Saturday for a 50 or so mile trip down the intercoastal.

I recently had the same problem with my 33 foot Tiara - I replaced the raw water pump impellers and the problem went away. Mine run at 150 at any rpm

Thanks. I replaced the raw water impellers when I had the elbows replaced. What engines do you have?

Hi pilot: did you read this from a few weeks ago?

"I'd guess that 70% of the overheating is due to low raw water flow. Another 20% due to dirty heat exchangers. Leaving 10% for the coolant side. On the raw side, I'd say most issues in these are due to clogged U coolers. Followed by clogged risers, followed by raw water pump issues, and not just the impellor. There is a cam wear issue, and scoring covers causing low pumping. On the input side, leaky strainer top gaskets, and fouling of the hull intakes. Once in a long while, a kinked or delaminated intake hose. If this is a salt water boat, and the risers are 4 years old, replace them. If the U cooler is original, replace it. "

You may also want to check if there is any debris in the u cooler as impellers sometimes shed rubber that clog the flow of water. Do both your exhausts throw the same amount of water at variable rpm?

I back flushed the u cooler before I had the impellers and elbows replaced. I haven't noticed any difference in water flowing out the exhaust. The issue only comes up when under way above 2000 rpm or so, not sure if it is flowing the same amount of water.

diver_dave said:

Hi pilot: did you read this from a few weeks ago?

"I'd guess that 70% of the overheating is due to low raw water flow. Another 20% due to dirty heat exchangers. Leaving 10% for the coolant side. On the raw side, I'd say most issues in these are due to clogged U coolers. Followed by clogged risers, followed by raw water pump issues, and not just the impellor. There is a cam wear issue, and scoring covers causing low pumping. On the input side, leaky strainer top gaskets, and fouling of the hull intakes. Once in a long while, a kinked or delaminated intake hose. If this is a salt water boat, and the risers are 4 years old, replace them. If the U cooler is original, replace it. "

Click to expand...

No, I didn't see this. I did notice the strainer basket on the port side the bottom came off and needs to be replaced.

My money is on zinc clogging the U cooler. A water backflush will not dislodge it, you need acid or a disassembly of the bottom cap on the cooler clean and inspect.

diver_dave said:

My money is on zinc clogging the U cooler. A water backflush will not dislodge it, you need acid or a disassembly of the bottom cap on the cooler clean and inspect.

Click to expand...

Thanks Dave. Why are you zeroing on the U cooler? Is taking off the bottom cap and cleaning pretty easy? Or do you recommend acid?

I did the acid thing ( half water / half muriatic acid) a few days ago and while it fizzed for about 5 minutes and sat for another 10, it did lower my cruise temperature about 10 degrees to 160. I took a short cut and only disconnected the two hoses and pour in the mix using a flexible funnel. You can clearly see a discolored effluent coming from the cooler ( one in....one out)

I did de-solder the u-coolers 2 seasons ago and really observed some cleaning actions in the cores but I did the tops. They sweat back on like any copper pipe joint and with a little Crusader Blue spray, look as good as an out of the box, new one.

One thing keeps me thinking however. I mentioned this to some friends who brought up the fact that Crusader considers this a "wear item" and is slated for replacement at intervals. That is fine and dandy but as I ALWAYS question replacement need having so many years of restoration experience in motorcycles, furniture and Victrolas. I need to be shown WHY this is so. I read and understand the way it works and the problems associated with its' failure but with my observations in disassembling some old ones (just for the fun of it), they seem "re-usable" for lack of a better word.

So one of two things will happen....I will be totally screwed for being stubborn as oils and water mix in the weak, broken core OR....I will get several more years out of the cleaned and re-painted unit. As the costs rise, I am hoping for the later.

IF you do decide to remove the upper and/or lower caps, a cleaning type bottle brush may prove to work wonders. Don K...Thanks Again

Sorry for the long winded post but the sleep aid has'nt kick in yet

Sounds like the U coolers are a common theme. I will have to check it out tomorrow. I am a novice mechanic so not sure I am up for disassembly. Any ideas on why the coolant level in the coolant recovery tank is fluctuating?

the oil coolers clogging due to lack of maintenance (routine changing) of the zinc pencils is pretty common. I'm incline to think the acid flush route is quicker in the long run though a bit hazardous for the first timer. Like DD said, a water backflush won't remove the zinc 'parts' as there is nowhere for them to go.

The coolant tank level should change but only as the engine temp changes. once up to operating temp, it should be stable. Most will rise a little as the coolant heats and expands. Once the valve in the cap closes, it should stabilize. Likewise, as things cool down, the valve in the cap will open and the contracting coolant will create a pressure drop and draw fromm the bottle.If it is fluctuating once at operating temp, it indicates other cooling issues, depending upon the specific changes.

Get the cooling restriction resolved first, and if the level in the bottle continues to change, then find its cause.

Sounds like a plan. Can anybody point me in the right direction on a guide on how to flush the u cooler with muriatic acid and not mess anything up? I have a knack for doing that sometime!

Knuckle's description pretty much covered it. Some clear PVC hose - 1.25" ID - from the hardware store makes it easier. You pretty much fill it up, let it "fizz", and then flush it out with water. 10 minutes is usually long enough.

Mark is right...I happened to have a long funnel and the tip is flared progressively larger...With a little pressure into the u-cooler fitting, it sealed enough to pour directly into the cooler. It will push remaining raw water out on the other side of the cooler so Mark's suggestion for that 1.25" hose is a great way to direct the effluent liquids into a container

By the way: Knuckle47 comes from the great LAST year of the Harley Davidson 1947 knucklehead. It was my personal bike while I was actively restoring motorcycles. Started 1st kick every time. Looked like a rat but what a all original great ride...When AOL FIRST STARTED...they asked for a "screen name". Everyones was so odd, I chose "knuckle47"...THAT was probably 20 years ago...it stuck ever since.

So Mark...you are half shark and Dave must scuba dive ?

I know its off topic but in case you're interested in old bikes

Ok guys..muriatic acid flush of the u-cooler complete. I rigged up an input/output hose with some flexible tubing. Definitely had some pretty nasty stuff that came out after the flush. Hopefully that will do the trick. Will report back tomorrow night after I give it a run.

Nice bikes knuckle!

Now...can you guys help my with my ac. The pump after the strainer is vibrating and making noise. I cleaned the strainer which was quite dirty but is still making a bunch of racket. The output water does flow but not for a few minutes..unlike it did before where it flowed immediately. Any ideas?

So, I guess you fly? Here's my thimble of knowledge. The water pumps used for air conditioning cooling are typically a magnetic coupling. This means in order to isolate the seawater from the motor, the magnet spins the impeller rather than directly attached to the armature. These pumps also do not really suck water as much as the push water thru the system. They need to be placed in a position that provides water at the impeller just by opening the seacock. Since your strainer was quite dirty, you may have some debris that is binding within the housing of the impeller or has worn the magnetic space and has created more slop in the housing that can vibrate. Little Giant pumps have a ceramic shaft and spacers, Cal pumps have just a small shaft and March pumps have epoxy housings that I have not any experience with. You can open the impeller housing to clean and inspect the parts just watch out for the o-ring seal which is easily replaceable. I have used these pumps for decades in saltwater aquariums....when I had gotten a boat that had air conditioning, I was surprised to see the exact same pump sitting in the bilge. Having added an additional A/C unit in the flybridge, I did more research on the water pumps to lift the water to the unit on the bridge at the required flow rate....thus, I became a water pump genius... Good Luck

Al hit the key - the bulk of those pumps are NOT self-priming. They are supposed to be mounted below the waterline to ensure a good waterflow. Unlike Al, I can only speak to the March units. As long as they are wet and supplied "clean" water, they will last a long time. If fed 'dirty' water, they won't last long. Parts are available but not anywhere. I found the best prices, a while ago, were from a chemical processing supply company. Another 'feature' on the march pumps, the marine ones anyhow, is some of the colling water is tapped and flows thru that epoxied housing, cooling the motor too.

If you don't know which kind you have, do a www search, look at the pics, and find the match. The common March numbers are LC-2 and LC-3 for the bigger units.

Hey Mark....I like that feature. I never had a March pump as they were always a bit more costly but that is a very good idea. Those Little Giant pumps are also sold under several different names. But they are the same MD-4 and MD-5 are the big ones. My new A/C fly bridge unit is using a CAL 1200. Even though the head (height water is being pushed upward) is about 9 feet and each 90 degree fitting adds about 2 foot to the "head" of the pump, we have plenty of flow. If I can find a real deal on a March pump, I will pick one up ....SOMEDAY

Thanks guys. The AC has been working like a champ since I got it a few months ago. It just started the vibrating and making a noise last weekend. When it was doing it, it was still putting out discharge water. However, when i turn it on now it still makes the noise, the cooling water will flow but it takes a few minutes. I was thinking that could possibly be an o-ring on top of the strainer which the owners manual mentions but I didn't recall seeing. It is a groco strainer.

Hopefully I can get this cooling issue resolved so I can move on to tearing it apart. It is HOT outside .

Al - I think those 90 deg elbows add a bit mmore than 2 ft equivalent hose length.

CTII - when the strainer leaks, water usually will flow out, as all that stuff should be below the waterline. Those noises indicate something is worn or there is a foreign body in the pump cavity. Either way, an inspection of the pump is warranted.

Thanks Mark. What is the best way to inspect the pump for debris? It looks pretty straight forward to take off with four screws but not sure where to go from there.

Updated on the original problem. After performing the muriatic u-cooler flush last night I had high hopes that the issue would be resolved. Unfortunately when I ran the boat today the problem is still there. I ran it for 1 minute at 180 degrees with a 2000 rpm power setting. Soon after I pushed it up to 3000 rpm the temperature started to climb. After approx 45 seconds to a 1 minute the temp was up to 200. I pulled the throttles back and the temp soon corrected itself to 180. On return to the slip after a day of hanging out on anchor I noticed the port motor's exhaust was steaming pretty good. The temp on both motors was at 175 degrees and stable. What's next?

CTII pilot said:

I noticed the port motor's exhaust was steaming pretty good. The temp on both motors was at 175 degrees and stable. What's next?

Click to expand...

I'm still thinking a lack of raw water flow. If the flow was normal, there would be very little steam. What is the service history of the raw water pump? Also, has the heat exchanger had any service, similar to what you just did to the U cooler? I have seen several U coolers with about 17 of the 21 total tubes plugged with zinc. Acid will eat these away, but without taking off the bottom casting to inspect, its hard to know for certain all the tubes are open. Have you taken the cover off of the HE, near its zinc pencil?

Ditto on the insufficient cooling water.

What did the old impellers look like?

Have you check the belt tension since the pumps were serviced? I've seen too many that needed a second tensioning session, especially after removal for service.

Dave's idea about water flow seem right to me also. I just replaced the elbows on one of my 1992 454's and even though they are under 4 yrs old, there was enough corrosion in those small cast holes to begin the development of issues identical to yours.

It is safe to say that your elbows may not be the problem but if you think about the fact that the raw water is what extracts the heat from the coolant and oil, if there is not enough flow thru the system, it gets hot and steams. I had taken off the end caps from the heat exchangers and ran a brass brush through all of the holes, cleaned the u-cooler and changed the impeller in the raw water pump and it all helped a LITTLE but it was the exit flow that became impeded and as the reduced water flow met the hot exhaust gasses..the gasses won....presto 170's now 140 to 160

By the way, I would like to meet the Crusader engineer who designed those elbows and the mounting nuts placement. I guess that's why there is a new design. Three out of four nuts took 30 seconds to remove, the fourth turned 1/32 of turn with each application of the wrench. I brought one of my cheapo 9/16" home to meet my grinder


PS, did you get my reply?
Apparantly Mark and I were typing at the same time and I did not read his reply until mine posted but my water pump drive belts need tensioning 3 times more than my other belts to the alternator

I haven't opened the heat exchanger yet. Someone did say something about taking it to have it boiled to remove corrosion. I will open it up next and take a look.
The raw water pump was just replaced in May. The engine had the same issue prior to the impeller being changed. I didn't see the old pumps because I had the mechanic do it when he was changing the elbows. The pumps had just been changed last August so they were fairly new and didn't have many hours on them.

Also, the ac water pump is a march pump. It is connected directly to the strainer and is going to be tricky to somehow get if off to inspect/clean.

knuckle47 said:

I brought one of my cheapo 9/16" home to meet my grinder

Click to expand...

Yes! I took a 9/16" combo wrench, cut it in half, and ground down the box side to take out some wall thickness. It fits great. When you need hi torq, put on a second box over the "stub" and it gets you a way to get a "90" on the wrench.

Two recent impeller changes.....????

Wonder if it happened to have been ignored and then the vanes separated. As noted earlier, they usually lodge in the u-cooler if they separate. The muriatic acid usually doesn't touch them. This is where that water 'backflush' may be helpful.

Before taking that task on, you may wanna check the flow of the raw water thru the system. I'll find the flow rate chart and post it following this one.

How did they connect the ac pump directly to the strainer and mount it securely? A picture of that would be worth the effort to get.