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Uneven exhaust waterflow on 454bs FWC

"I notice on my last couple of

"I notice on my last couple of zips here in SF Bay....that I have less water coming out the Stbd Exhaust than the Port??? No noticeble difference in temprature so I am thinking risers are getting clogged. Is this a reasonable assumption? Impellers, heat exchanger, strainers, hoses are all relatively new. (less than 2 years) If the thinking is changing out the Risers which I think are +10 years old...then any tips on doing that would be much appreciated.

I have 1986 454's Crusaders FWC with 800 hrs. As always I appreciate the help"
 
"temp on the gauge or temp of

"temp on the gauge or temp of the elbows; the later should be evident by hand.

If they are 10 years old +/-, their replacement is due.

Many posts on the crusader board for doing the riser swap - just search for them. Anti-sieze for the reassembly is a must as are new gaskets. Gasket orientation is critcal, too. before you order/purchase, make sure you get the part names correct - osco's www site is good for reference."
 
"Please check the easy stuff f

"Please check the easy stuff first. If it were me I'd be looking for any blockage in the system, especially at the u-cooler and then at the impeller first.

But thats just me, I like to go for the easy stuff before I go too deep........"
 
Here's another case where

Here's another case where an infrared temp gun is invaluable. I'll bet one side is running much hotter than the other due to a blockage in the riser outlets.

Jeff
 
"Mark is correct on those gask

"Mark is correct on those gaskets... Every thing I had looked at FAILED to clearly point out the TYPE of gaskets used...Since they all look alike if you just quickly look at them, you WILL screw up...The diagram he posted certaily shows the differences...

Yup, Mine were wrong...."
 
"Maybe I missed something orig

"Maybe I missed something originally, or maybe I was just assuming you were referring to the amount of water coming from the port engine versus the starboard engine. But it seems that folks are responding as if the water varies from the port side versus starboard side exhaust on a single engine, in which case I would certainly agree with the clogged riser theory.

If talking one engine versus the other then I'd move upstream in my search before ripping off risers."
 
You are correct in that I was

You are correct in that I was referring to a "Port" engine versus a "Stbd" engine. Whats throwing me is by looking upsteam would indicate I would find a blockage or reduced water flow i.e. impellar or Heat exchanger. But...why am I not seeing is difference in temprature which would point directly to them as the culprit. I plan on taking FastJeff's plan of laser temping top to bottom to isolate.
 
"Richard; in salt water, FOUR

"Richard; in salt water, FOUR years is the life of the double wall risers. Many of these iron castings have a date code cast in. Ten years is almost unbelievable in salt. I've had OEM risers totally plug right at the 5 year mark."
 
"It has been in salt for two a

"It has been in salt for two all others were in the Sacramento Delta which is mostly fresh but lot of silt....so impellars where changed frequent but risers were not. I will look closer on the risers for a "date code". The reality is I need to change them as I know for sure they are older than 4. Thx, Diver Dave."
 
"One reason for not seeing the

"One reason for not seeing the difference on the gauge is that you have reduced water flow but it is still sufficient to remove the 'excess heat' from the heat exchanger. Rest assured, without corrective action, the water flow will continue to decrease and the gauge will rise.

Most likely your risers are the cause due to the temp gauge being 'normal'. The other likely restriction point is the bottom of the oil cooler. When this issue arises, the temp gauge will increase above normal, especially with elevated RPMs, due to the lack of 'heat capacity' of the raw water system at the HX."
 
"I have just stepped up and sp

"I have just stepped up and spent the money on replacing the risers,gaskets,bolts. Also will replace raw water impellers. I agree with you...and will update when completed."
 
"Well if you know where it is

"Well if you know where it is then all you need to do is to remove the hose that feeds the inbound side and check for any blockage. Trash that you pick up from the water inlet always seems to accumulate there. If theres trash accumulated then you'll feel it with your finger, assuming it's in a position that you can't see. If you feel trash then remove the hose from the outbound side and flush thoroughly. A piece of coat hanger comes in real handy as well."
 
"The oil cooler has two potent

"The oil cooler has two potential issues: 1) the trash at the inlet Tailspnr described (minimal if a good strainer is used) & 2) erosion of the zinc pencil where the 'flakes' restrict the raw water flowing up the inboard tube.

There are a variety of 'ingenous' methods that have been described here - use the search button, enter "oil cooler" as the keyword and select "Crusader Marine" as the search topic."
 
"I don't usually get into

"I don't usually get into the discussion concerning salt water issues since I have always been in fresh water. But since you mentioned silt, I have to weigh in, having boated on the Mississippi River for a number of years. Silt is the enemy of water pumps; it wears them out. Wear on the front and back plates allows bypassing of water from the high pressure side to the low pressure side. Changing the impeller alone will not solve the problem. I suggest you drop in a new pump in the starboard side and see if that provides more water flow. If it doesn't, you can resort to the more difficult things to address. If it does you can order a new pump to serve as your spare.

Chuck Hanson"
 
"Good points Chuck.

he can


"Good points Chuck.

he can always change the wear plate, back cover, and cam, too. Probably better to buy a full kit than the individual parts though. I'm sure that's better than the whole pump, $$-wise."
 
"I have the same issue. Replac

"I have the same issue. Replaced the impellor, U cooler with no luck. Risers are 14 years old. I think these are next. R, Keep us posted, as will I on your progress."
 
"There is a diagnostic method

"There is a diagnostic method of measuring performance of the raw water system. You can remove the RW drain plug on the heat exchanger and pipe in a 0 to 15psi gauge. If you have a good working system baselined, you can read the gauge and tell if the risers are clogged (too high pressure), or the pump is not moving enough volume (too low pressure).
This method may not have 100% certainty to point to one part or another, but it can lead one to look in the correct direction. A flow meter is not much help, since quite a number of defects can cause low flow."
 
"I recall that about 4psi is n

"I recall that about 4psi is normal on my engines, so you do need a low pressure gauge, and there is some fluctuation in use due to exhaust back pressure."
 
Well I was able to get one ris

Well I was able to get one riser off this weekend and although their was corrosion it did not look bad. (the serial number confirm that they are over 10 years old....so not bad wear) But I am confused on the gaskets from the top of the 12-inch riser back. The parts distributer sent me three hole gaskets....and when asking about which direction to install...they contend they have sent me the wrong ones and what I need is a single-hole gasket. Can this be right?? I am going to block three of the exhaust ports with just a gasket? Their contention is that the gasket will allow the the coolant to fill up to a higher level. I have asked them to fax me a diagram. Really buying time to see what the "pros" think. So what do you all think? Is their a diagram that I can see somewhere on line. to recap; 454 FWC 86's.
 
"The annular slots are where t

"The annular slots are where the cooling liquid flows. The exhaust only flows thru the center port. This design has worked for well over 25 years .... (properly assembled) so, if its works, why mess with it?

There's more than one member that will attest to the fustration that results from incorrect assembly."
 
Well the water flow is solved.

Well the water flow is solved. Took a few bucks (New risers and oil coolers) but as they were original parts on this tough 1986....they were long over due. The exhaust risers really did not look bad in terms of corresion but the oil coolers had zinc sticks piled up in the bottom and probably was about 40% clogged. So I am good to go. Flow looks good and now a little more added steam to follow me around the bay. Thanks for the help. I am now on to a new post with a funky carb.
 
The zinc inserts into the bott

The zinc inserts into the bottom of the oil coolers are sometimes referred two as "pencils zinc". He is suggesting I change them out monthly when they still have a bit of girth to them and won't break off and sit in the bottom of those coolers and clog it up.
 
"Yes, much cheaper to buy a ba

"Yes, much cheaper to buy a bag of pencils vs the pencil with the pipe plug.

My owner's manual lists this as a 30 day item, same for the HX pencil, too. If you use the boat infrequently, you may be able to extend the interval; by how much will be driven by your specifics.

Its worked pretty well for me over the past couple of decades....When I find the cooler clogged, its usually due to my maintenance irregularities. Just food for thought."
 
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