Symptoms of a bad raw water impeller - both engines running hot

mrsrobinson

Well-Known Member
Mar 9, 2006
7,704
Virginia
Boat Info
2001 380DA
Engines
Caterpillar 3126
My new to me 2001 Sea Ray 380DA with Caterpillars 3126s ran at 180 degrees on plane for her first 12 hours of use. I put her in mud (at idle speed) coming into the new to me slip she is now in. Both engines overheated. Both sea strainers were packed, and I mean packed, full of black crude looking thick mud. I cleaned them up, let the engines cool down, fired both up, brown mud shot out of the exhaust, and they have both been running under 180 degrees at the dock/slip. Good water flow at the exhausts, both the underwater and sides.

We tried to replace the aftercooler zincs this Saturday while we were doing some other service. I tried one on each, the zinc broke off inside the after cooler, or was already broken off, so I stopped.

After completing the service, I put her up on plane then/Saturday for the first time since the mud. Both engines slowly, very slowly, creeped up to 200 degrees and then slightly over. When I dropped her down to idle, they quickly went back to 180 degrees and stayed there.

If my memory is correct, I had a bad raw water impeller in my 330DA and it ran hotter at idle, cooler on plane.

Mechanic thinks something is clogging up the raw water system. Whatever it is it's happening to both engines. Sound like the raw water impellers? Aftercoolers? Other?

Thanks
 
The engine heat exchanger is still somewhat plugged up with mud. The mud will also take out your impellers; especially in the 3116 and 3126 engines. There is no phenolic liner in those pumps.
I had to change the impellers on my 3116 engines every year and there was always some damage to the vanes. On my QSM11's, I just pulled and replaced the impellers; 5 years on them and no damage apparent. the pumps have the liners.
 
Thanks, heat exchangers sounds like a likely source, at least a good place to start before I scrape my knuckles trying the impellers. I have never worked on these, is is a simple as pulling the caps, spraying water in, to flush? Will I need to pick up any gaskets/seals/o-rings to replace?

Mechanic doesn't think it's the heat exchangers since they are running under 180 at the dock, at idle. He's wondering if an impeller fin is lodged in the system. I guess it's possible this could happen to both engines at the same time.
 
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Thanks, heat exchangers sounds like a likely source, at least a good place to start before I scrape my knuckles trying the impellers. I have never worked on these, is is a simple as pulling the caps, spraying water in, to flush? Will I need to pick up any gaskets/seals/o-rings to replace?

Mechanic doesn't think it's the heat exchangers since they are running under 180 at the dock, at idle. He's wondering if an impeller fin is lodged in the system. I guess it's possible this could happen to both engines at the same time.

I’d see if you can backflush the raw water side the same way it’s recommended to run the barnacle buster. Hell, while you’re doing that once it’s clear you might as well clean the system anyway
 
Thanks, heat exchangers sounds like a likely source, at least a good place to start before I scrape my knuckles trying the impellers. I have never worked on these, is is a simple as pulling the caps, spraying water in, to flush? Will I need to pick up any gaskets/seals/o-rings to replace?

Mechanic doesn't think it's the heat exchangers since they are running under 180 at the dock, at idle. He's wondering if an impeller fin is lodged in the system. I guess it's possible this could happen to both engines at the same time.
An impeller fin will not do anything but reduce the flow that the fin provides.
There is a lot of excess cooling capability in the system so cooling at low RPM/load can occur with an almost completely clogged heat exchanger but as the heat load increases that will be overcome.
The cap on the side of the turbocharger can be removed without risking dumping the engine coolant.
Pull the two hoses off the other cap and flush from the turbocharger side to the hose side. You can carefully rod the tubes with an aluminum weld rod or wood dowel while flushing with water.
 
As a note -
unless you see the upper half tubes clogged in the heat exchanger when you remove that cap you only need to clean out the lower half. Water from the pump flows into the lower half tubes and returns in the upper half of the tubes.
 
if equipped with dripless shaft seals STRONGLY suggest you also yank those lines and confirm clean, strong flow to the shaft logs.

Found one of mine caked full of marine growth, restricting flow.

Removed BOTH risers/elbows for good acid bath and cleaned shower head.

Now is the time to get at all that mud and whatever growth might be in there.

BEST !

RWS
 
Thanks, do I need to replace a gasket/seal when I remove the cap? Checking so I can buy it ahead of time to have with me.
 
Ordered these rings, thanks!

6V-5504: SEAL O RING
5F-3999: SEAL
3F-5792: SEAL-O-RING

I have not welded since I was a teenager, I'll see what I can find at Lowe's.
 
As a note -
unless you see the upper half tubes clogged in the heat exchanger when you remove that cap you only need to clean out the lower half. Water from the pump flows into the lower half tubes and returns in the upper half of the tubes.

>>>>>>>>>>>>>>>>>>>>>

wonder if you could simply remove all the raw water hoses and backflush each individual cooler with a garden hose.

heat exchanger, fuel cooler, transmission cooler, showerhead, aftercooler - EVERYTHING - just don't know how you can do this all and avoid getting water into the engine where it should not be.

Certainly, backflushing the trans cooler and heat exchanger with the hoses removed is safe.

RWS
 
Showerhead? How will that help the engines run cooler? ;)

"avoid getting water into the engine"

I assume all raw water flow from the seacock to the thru hull exhaust is ok to backflush and cannot get into the engine. Someone please correct me if I am wrong.
 
>>>>>>>>>>>>>>>>>>>>>

wonder if you could simply remove all the raw water hoses and backflush each individual cooler with a garden hose.

heat exchanger, fuel cooler, transmission cooler, showerhead, aftercooler - EVERYTHING - just don't know how you can do this all and avoid getting water into the engine where it should not be.

Certainly, backflushing the trans cooler and heat exchanger with the hoses removed is safe.

RWS
You could never flow enough water with a garden hose to flush it out. It is a tube by tube cleaning to get packed mud out.
 
Showerhead? How will that help the engines run cooler? ;)

"avoid getting water into the engine"

I assume all raw water flow from the seacock to the thru hull exhaust is ok to backflush and cannot get into the engine. Someone please correct me if I am wrong.

the loop is usually made by back feeding the big raw water hose that feeds the riser and the exhaust should be the only place water could enter the engine. If you feed that hose and catch from either the outlet of the impeller housing or remove the impeller from the pump and catch it from the hose connected to the strainer (this makes sure the fuel cooler gets cleaned) you’d have a safe reverse loop that won’t fill the engine.

That will not clean the riser/shower head though so you’ll have to pull the exhaust hose and get a look at those passages
 
the loop is usually made by back feeding the big raw water hose that feeds the riser and the exhaust should be the only place water could enter the engine. If you feed that hose and catch from either the outlet of the impeller housing or remove the impeller from the pump and catch it from the hose connected to the strainer (this makes sure the fuel cooler gets cleaned) you’d have a safe reverse loop that won’t fill the engine.

That will not clean the riser/shower head though so you’ll have to pull the exhaust hose and get a look at those passages
It would be rare the exhaust shower head would be plugged up as it's holes/passages are larger than those in the gear cooler. Regardless, remove the raw water inlet hose from the underside of the exhaust riser and remove the flex connection on the exhaust at the riser. Pack a rag into the exhaust so it is plugged from water intrusion and with a hose back-wash the riser water jacket from the shower side and allow to flow out where the hose from the gear cooler attaches.

Get it back together and start the engine so any moisture that may have gotten to the turbo's turbine side can be evaporated/expelled. It's not a big deal but you don't want moisture sitting at the blades for any length of time.
 
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Ok, I now understand what the shower head is; I thought someone was joking about the head/shower.
 
Ordered these rings, thanks!

6V-5504: SEAL O RING
5F-3999: SEAL
3F-5792: SEAL-O-RING

I have not welded since I was a teenager, I'll see what I can find at Lowe's.
A .22 cleaning rod will also work in a pinch.

And if your going to accumulate what you need...2 pack impellers. If you have a 2"-2-1/2" bolt, getting them in and out isnt as bad as you think. The first time has a learning curve, but it can be done on both side in 1-2 hours. The oil gallery is close, but just enough room to sneak them in and out.

https://marinepumpdirect.com/two-pack-sherwood-17000k/
 
Thanks, yup, I have those 2 on my boat. We were going to replace them this weekend while doing the other service, but I had some clarifying questions I needed answered. I have the bolt as well. I had to order 5 of them, mailed one to @Strecker25 yesterday, I have 3 more if anyone wants one.

"The oil gallery is close, but just enough room to sneak them in and out."

Oil gallery?
 

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