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Low profile elbow replacement

S

stugiv

New member
Greetings all,

Searched thru the forums but didn't find anything specific to my question.

I'm considering replacing the elbows on my starboard '97 454XL as its running a little warm & I don't know the age of the elbows having just bought the boat last year.* The Crusader part # for the elbows is 98126 for the low profile model which is apparently out of production according to the internet searches I've performed.* Barr seems to be the only one that makes a comparably sized replacement or I can try to switch to the 9015 which are 1.5" taller.* I measured & have a good 2"+ clearance above, but I'd be more comfortable with some air space around the elbows rather than having them almost in contact with the sound insulation foil.

Opinions appreciated! Thanks.
 
The taller ones may need more exhaust hose to make a good connection. get an IR thermometer and measure the elbows...and the rest of the system. They may be due to be changed; could also be the oil coolers being restricted or the raw water pump. better to find the problem and fix it vs throwing parts at the issue.
 
I just picked up an IR thermometer the other day, but haven't had a chance to try it yet. The raw water pump was replaced last year when I purchased the boat, but I guess I can pop the hoses off the oil cooler to see how they're flowing.

Unfortunately the fuel pump on this engine conked out last night, so I've got to see about that first. I tried to reverse the polarity, but the pump appears to be frozen. I can feel it twist slightly & hear a slight clunk but no movement.
 
Fuel pump replaced & it appears to be running fine. Back to the warm temps, where else should I spot check with the IR thermometer other than the exhaust elbows? Also, how do you judge if the quantity of water flowing thru any given hose is sufficient? I pulled the hose off that comes out of the oil cooler at idle & it seemed fairly good but not sure what it should be.
 
Water flow is best assessed by measuring it...if you can accurately assess flow from a hose with your eye, you should change your career field.

IR measurements - add T-stat housing, exhaust manifold inlet/outlets, HX inlets/outlets (both raw and closed sides) and the oil cooler inlet/outlets and you should be adequate.
 
Thought I should follow up on my progress. Prior to reading makomark's post above, I had used the IR gun to measure the elbows & thermostat housings. The elbows on the stbd engine were in the 155-165° range while the port engine was 160-170°. Both thermo housings were right around 165°.

While discussing the issue with a boating friend, he suggested back flushing the oil cooler since that would be the first place impeller pieces would get stuck if it had come apart in the past. I popped the hose off the heat exchanger & the size is close enough to the garden hose to allow the clamp to make a decent seal. Removed the hose from the oil cooler inlet & pushed some water thru for a minute. I did find a few small black chunks of something that may have been from the impeller. For good measure, I also plugged the garden hose into the hoses that lead into each exhaust elbow to flush them. Finally, I opened up the ends on the heat exchanger & ran a coat hanger thru some of the tubes that were accessible. Honestly, the exchanger only had a little scale at the ends of a couple tubes around the outer edge & otherwise looked clear.

For good measure, I then performed the same procedure on the port engine. Took the boat out several times over the weekend & the port engine is running at a steady 170-175° & stbd @ 175-180° by the temp gauges. This is a 5-10° improvement on port & 10-15° improvement on stbd. I'm pretty satisfied with those temps for now, unless someone wants to tell me I'm being naively optimistic! ;)
 
Well, as I suspected it was too soon to declare victory. I used my new IR temp gun to record the following temps after getting the engine up to temp. Temps look fine until you get to the HX raw inlet, which I suspect is because the whole HXer was quite warm at that point. I should note that there was quite a bit of variation in temps depending on where I pointed the tool, so for consistency I took the temps off the top of the metal housings or connection points & not the hoses.

My amateur interpretation is that the raw water is not able to leave the HX quickly enough to carry away the heat, leaving me to my original suspicion that the elbows need to be replaced. As I noted before, I opened the HX & there appeared to be little buildup that would limit water flow or heat transfer.

Feel free to let me know if I'm reading this incorrectly!

temp chart.jpg

Edit: I should add that the engine temp gauge was 170-175° on the port side & 190-200° stbd side during the run where I took these temps. I found it interesting that the IR reading of the housing itself was only about 175°, but the other readings tell the story.
 
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The stbd exhaust elbows are too hot and the port ones are borderline too hot. The insignificant temp rise in the RAW flow on the STBD HX says it is NOT absorbing any heat...Also, your HX closed side measurements are backwards - the outlet has to be cooler than the inlet.

you can also see that your measurements are close but notall 'real'. I suspect it is due to the spots you selected to take the measurements and their locations being a little distance from optimal. overall you did pretty work getting the data.
 
Heh, now that you point it out its obvious those closed side numbers are reversed! I was getting a lot of variation in the numbers by just moving the measurement spot to slightly different spots. It was also hard keeping the IR gun steady while the boat is moving.

I'll get some elbows ordered. Thanks for the help!
 
i used a flourescent orange marking crayon to ID my measurement boxes (for the red dot)...I believe a consistent measurement is more important is early problem detection - absolute values are nice but a 'change' represents the onset of an issue...just my two cents
 
My IR gun has a red dot but that is to be used for aiming purposes only. Depending upon how close or far away the gun is from that point your measurements could be off because the actual beam gets spread out quite a bit...sort of like a shot gun. The closer the gun the more accurate the readings, so try to be a consistent distance for each measurement, assuming your gun is similar.
 
Hi Mark,

Where do you find a flourescent marking crayon ? Is it the "Crayola " variety or something special that won't melt away?....Al
 
Hi Al!
don't know the retail source...I got it from one of my welder buddies. hasn't melted yet and with my black paint scheme it sure is easy to find. Next time I go down to the boat, I'll see if it has anything legible on the wrapper.
 
Sorry Al; there isn't any wrapper on it...maybe a welding supply shop? I know they also have what I call thermometer markers = those that will melt at a given temp = if it is one of those, it's temp is well over 200.
 
Welp... dropped a new set of Barr elbows on & no improvement. Actually, that's not completely true as the temps on the elbows on the problematic engine are down 20° or so. Still running at about 190° by the temp gauge. The local dock mechanic recommends removing the oil cooler & having it boiled out. I'm not going to get around to that until next week at the earliest, so I'm thinking of trying to measure the water flow before & after the cooler.

I'm thinking the best way to do it is to use a 5 gallon bucket & time how long it takes to fill at idle. It shouldn't be too difficult to remove the respective hoses & direct it into the bucket. If there's no difference, then I'm thinking there might be a restriction at the intake. I read during my searches here that 11gpm might be the proper flow rate for this pump, though I'm trying to verify that on the manufacturer's website.

Open to suggestions.
 
Good idea. You'll be surprised (as I was) at how little water flows at idle.

Are you absolutley sure there's no air leak before the raw water pump? The smallest amount of air reduces cooling tremedously.

Jeff
 
Well, I did a flow test comparison between the two engines. They were both cold so I was running them slightly above idle at ~600 rpm & directed the hoses I disconnected into a bucket that I had marked with a line at the 4 gallon level. Tried not to pinch the hoses but for the post oil cooler test I had to rest the bucket on top of the engine so it was pumping vertically the height of the bucket.

Starboard engine (troublemaker)
Pre Oil Cooler: 45 seconds
Post Oil Cooler: 65-70 seconds

Port engine
Pre Oil Cooler: 40 seconds
Post Oil Cooler: 45 seconds

Based on these numbers, the flow is about 5-6gpm at this rpm. It appears there may indeed be a blockage of some type in the oil cooler. I reverse flushed it again with a garden hose & there was a noticeable piece of debris that was ejected into the bucket, but unfortunately the bucket tipped over into the bilge & I couldn't find it.
 
Never mind that; you're getting somewhere now. Did you retest after the debris was eliminated?

Jeff

PS: Note that the "Pre Oil Cooler" flow was still lower on that side. Hummm...
 
I'm not too worried about the slight difference in time between the engines, I was doing the test by myself so there were a lot of distractions trying to start the engine, start timing, diving under the hatch to watch, etc.

I didn't run another timing test, but I did take the boat for a ride today & the starboard engine didn't go over 180°. Not convinced its definitely fixed yet, but perhaps I'll test the flow again if I can find someone to help me.
 
...." I was doing the test by myself "

Holy cow! That's like being a one armed paper hanger.

Looks like you MAY be okay. Sure hope so.

Jeff
 
For the flow tests, most factory manuals suggest repeating it three times to average out those distractions. Engine rpm is a key factor to making accurate flow measurements.

Sounds like the "zinc parts in the cooler" issue. Backflushing the cooler will get some but not all of the blocking pieces. If you search (probably the archives) you will find several posts where innovative members have used muriatic acid to flush the raw water side of the cooler. And, FWIW, if one engine has developed an issue, the other is likely to be right behind it....
 
makomark said:
For the flow tests, most factory manuals suggest repeating it three times to average out those distractions. Engine rpm is a key factor to making accurate flow measurements.

Sounds like the "zinc parts in the cooler" issue. Backflushing the cooler will get some but not all of the blocking pieces. If you search (probably the archives) you will find several posts where innovative members have used muriatic acid to flush the raw water side of the cooler. And, FWIW, if one engine has developed an issue, the other is likely to be right behind it....
Click to expand...

Will the muriatic acid harm the impeller in the raw water pump?
 
Probably. That's hydrochloric acid, and it's vicious stuff. Also, you wanna be really careful adding acid to water; if there's pockets of water hiding inside the pump, the acid can react violently and splash on you.

Jeff
 
Depends upon who's impeller is in the pump and how long you leave it in there as well as how far you dilute the acid. Most synthetic rubber compounds tolerate that stuff pretty well. also have to check the seal's compatibility. I wouldn't use the raw water pump to circulate the acid for several reasons.
 
@makomark: That makes complete sense to do multiple tests to verify if the flow actually matches factory specs. I was just doing a quick comparative test & I couldn't find anything definitive online as to the rated flow of the pump at a particular rpm.

Your zinc diagnosis reminds me that when I winterized last year, the water seemed to drain quite slowly from the oil cooler as if there was buildup around the pencil zinc. Sounds quite plausible.

In the meantime, I took the boat for another run to see what the gauges would read. Upon initial start, I noticed a cloud of rust in the exhaust water for a few seconds which I'm guessing is from the new elbows after the internal paint burned off. In the no-wake zone, the starboard engine with the new elbows got up to operating temperature slower than the port engine. The starboard engine then climbed to 190 (causing me a little stress), then within seconds it dropped to just below 180 (I assume the thermostat opened). Temps then stayed just below 180 during the run @ 26-2800 rpm, more no-wake rpms, another run & then back to the slip. The only time it snuck above 180 was right after coming off plane, but that makes sense as the reduced water flow at low rpm while the engine is still quite hot. Both engines go up a couple degrees at that point for a few minutes.

So far so good from my point of view. It looks like the thermostat might be a bit sticky & the oil cooler(s?) will need to be cleaned out in the near future. I'm hoping at this point I can do any additional work in the off season.
 
The flow data for a given pump is on Sherwood's www site though it is a bit coarse. If you are still interested, send me a PM with an email & I'll forward what i have as time permits. as a rule of thumb, you will need 7 gal/min @ 1000 RPM. I think I posted what I had so you can also search, probably in the Crusader archives, here.
 
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