PCM 409 engine impellers?

[agarabaghi]

When the tech came out to do the 25hours service in september he showed me a few things around the engine etc... he also mentioned how these engines like impellers and to make sure to check every 50hours....

My oil changes for 3 yrs are free from the dealer so when they came to do the oil change i had them drop off an impeller to replace. 

50 hours on this impeller (75hours total).... tech wasnt lying

Edited November 29, 2017 by agarabaghi

[oldjeep]

Looks like a lot of running without water.  I wondering they don't prime very well and you need to bump the throttle immediately on startup?

[agarabaghi]

not sure. boat has never been run dry, and never been hooked up to a fake a lake or garden hose. will see how the next 50hours go

[oldjeep]

Did they clean the missing bits out of your trans cooler?

[wakedncsu]

22 minutes ago, oldjeep said:

Looks like a lot of running without water.  I wondering they don't prime very well and you need to bump the throttle immediately on startup?

I have the PCM 409 in my A24.  This is exactly the scenario I have.  If I don't bump the throttle the pump won't prime and I'll eventually get an overheat warning.  Luckily we don't do much idling.  It's a crank up and go scenario.  When we first put in the water and I have to idle the boat to pick up my wife from parking the trailer and all that...I bump the throttle to ensure the pump primes. 

 

I have only replaced my impeller once in the two years.  The first impeller looked as good as it did brand new.  I do not have the issues you just linked in the slightest.

[agarabaghi]

Just now, oldjeep said:

Did they clean the missing bits out of your trans cooler?

I will have to check the transcooler tonight. They only did the oil change. i pulled the impeller myself. 

 

Does the manual have diagram of the transcooler?

[agarabaghi]

2 minutes ago, wakedncsu said:

I have the PCM 409 in my A24.  This is exactly the scenario I have.  If I don't bump the throttle the pump won't prime and I'll eventually get an overheat warning.  Luckily we don't do much idling.  It's a crank up and go scenario.  When we first put in the water and I have to idle the boat to pick up my wife from parking the trailer and all that...I bump the throttle to ensure the pump primes. 

 

I have only replaced my impeller once in the two years.  The first impeller looked as good as it did brand new.  I do not have the issues you just linked in the slightest.

We lower the boat off the lift and crank her up and immediatly reverse out of the slip. Ive never seen the tmep go up past 160F... will keep an eye on this new one. never got an alarm either

[agarabaghi]

i assume im pulling the hose off beofre #5?

[wakedncsu]

Just now, agarabaghi said:

We lower the boat off the lift and crank her up and immediatly reverse out of the slip. Ive never seen the tmep go up past 160F... will keep an eye on this new one. never got an alarm either

It takes minutes to overheat the motor.  I would guess between 5 and 10 minutes at idle to do it.  The only times I have had it happen are when we crank up on the lake and then get stuck talking to someone before heading out.  I'll forget to bump the throttle and then minutes later get a warning from the dash.  I can bump it right after the warning goes off and it will cool straight back down to 160.  If you are taking off the lift and not idling for long before getting on the gas, that shouldn't be an issue for you at that time.  Mine will lose prime anytime I sit for a while.  I have never taken the time to figure out what that time limit is.  I can turn the boat off while switching riders and it won't lose prime.  So that would mean more than a few minutes.  If I anchor at the sandbar for a while, I lose prime every time.  That is usually more than 1 hour.

[agarabaghi]

cant say ive had any issues. 

We do drain ballast in the slip and it just sits there idling with the engine on, no over heating...

 

[wakedncsu]

That is the hose.  

[agarabaghi]

is there a grate on the transmission cooler? I know my indmar had one i could just pick weeds n stuff out

[wakedncsu]

Once it's primed it is good to go till the motor sits for a while.  It sounds like you may have just had a bad impeller.  I recently looked at my current impeller while troubleshooting an overheating problem that turned out to be my thermostat.  It looked just as good as new too.

Mine has a grate on the end of it.  First time I took it off I found plastic in it.  Presumable from something being covered from the factory and not being removed before the first time it was cranked.  It wasn't too much.  I thought that might have been the cause of my not priming issues.  But that didn't solve it.  Since then I have spoken to more people with this motor that have had the same experience as I have.

[agarabaghi]

ill take a peak tonight. Ill prob hit 125 hours (next 50) before the new year so it shouldnt be too long till i check the impeller again.

[Wilbur]

I have the PCM 409 in my 15' A22 and I've never had any issues with over heating and my impeller looked good when I replaced it last.

I normally unload and just let it idle a good 15 minutes while I'm filling up all the tanks & bags and putting out of the 5 zone.

Do you guys, who are having priming/overheating issues, have a sea strainer?

I have a salt water package, which has a sea strainer and it always has water in it, so maybe that helps mine always stay primed?

I also flush my motor for about 5-10 minutes every time I pull it out and I run it from idle-2k rpms. I'm not sure where the transom flush hose enters the cooling system, but maybe that helps keep mine primed all the time too?

 

Edited November 29, 2017 by Wilbur

[shawndoggy]

All of my PCM impellers have looked like that at 50-75 hours, if you have the PCM belt driven pump, not the johnson pump like they put on the crusader 350s.  Sample size of one (just me) with 300 hours on my MB and 100 hours on the axis.  

Overheating on pcm is frequently related to an air leak (or at least it was on my ex343 in the MB)... everything could look fine but if there was a hose not tight enough or most likely the raw water strainer cup not "dern tight" then a small amount of air could be sucked in, which will cause temps to spike.  

I think temp spikes and impeller wear aren't necessarily directly related.

[Andrew63]

Is it just me or do the vane tips in the 1st post look hollow?

The old Johnson impellers have solid tip vanes.

Could be wrong about the holow tips, just lookingat the pic.

If they are holow, this would explain the short life span

[Raimie]

Is there a 'run-dry' impeller option for the PCM?

[JasonK]

I think the impeller on my 1990 had hollow vane tips.

 

[redflash]

Its the design of PCM`s raw water pump, when you replace your impeller look inside the pump body, the guide fingers inside look like a kitchen fork and are quit sharp, you`ll see why they wear quickly.

[agarabaghi]

yup thats what the tech said. wonder why?

[Raimie]

Wonder if anyone has replaced it with the indmar style water pump? Or, how hard that would be to do..

 

Edited December 1, 2017 by Raimie

[COOP]

On 11/29/2017 at 8:42 AM, oldjeep said:

Looks like a lot of running without water.  I wondering they don't prime very well and you need to bump the throttle immediately on startup?

Yup, the PCMs dont prime well at all. 

[agarabaghi]

dont think this has anything to do with running dry or priming. like others have said i think the housing intentionally does this

[shawndoggy]

1 hour ago, agarabaghi said:

dont think this has anything to do with running dry or priming. like others have said i think the housing intentionally does this

Agree.  Never had a problem with my PCM systems priming. But the pump housing is a bit of a cheese grater for the impellers.  Better make sure to put that on my list for spring.