Over heating

[Jeff Kaplan]

Must be the summer for overheating.  On #219 w/ M25, motor usually runs about 165-170* @ 1800rpm's, except when motoring into heavy head winds she might climb to 185*.  Last weekend temp climbed close to 200*.  Went out today with new impeller+ gasket plus new thermostat and gasket.  A friend helped me and when done, fired her up and found not pumping any water.  Shut down engine, opened up raw water strainer to check for blockage, found none, water gushing in.  Removed water pump, oberdofer, impeller cover again, checked impeller, not problem.  Went thru this more times than I want to say, wasting precious sailing time now, and still no water coming out of exhaust.  Opened bleed screw, no help.  Installed another impeller, still no luck.  Checked all hoses, no problems.  I am perplexed, my friend is a mechanic and we did all the right checks.  What am I missing, can't figure out why no water being pulled thru.  Any suggestions or helpful ideas will be greatly appreciated.  Thanks,

Jeff

[pablosgirl]

Hi Jeff,

A few thpings to try:
1) was the replacement paper gasket really thin?  A few of us have found that a thicker gasket will cause the impeler vanes not to seal against the cover.  The back of the pump housing can wear and cause the impeler vanes not to seal against the back of the pump changer or the cover.  You can sand the pump housing face to lessen this distance, but you must not remove than necessary to restore the proper tolerance.
2) was the cover plate smoth and flat?  I have found that the soft bronze cover plate wares and I lose the seal between the impeler and the cover.  You can true and smoth the cover by placing a piece of 100 grit sandpaper on a flat surface and rubbing the cover back and forth on the sandpaper to remove any groves or scratches.  Progress through finer grits until you reach a mirror polished finish (usually 1000 or1200 grit will achive a mirror finish).
3) check for impeler blades loged in the hose leading to the heat exchanger or in the heat exchanger itself.  Also this would be a good time to check the zink in the heat exchanger if you have not done so reciently.

Hope this will help

Paul

[Steve W10]

Hey Jeff, it does sound like you hit the big points and Paul has some good suggestions there.

Although if you haven't found blades missing on previous impellers, and you've had the exchanger apart previously, it may not be a clogged heat exchanger.

Not sure if you put the impeller in dry or lubricated?  Anytime I pull my impeller I coat it with petroleum jelly before installation to help with the initial priming - not too much, just enough to help create a slightly better seal .  Once water is in there it works great but initially without lube, air can make it's way by; I've never had a problem when using the jelly.

I know that's pretty simple, but that's where I usually like to start.

Unfortunately that doesn't really address your initial rise in temperature.  Could it be coincidental with a low coolant level, air pocket, or even leak in the glycol system? 

Steve

[prh77]

I also like to fill the raw water inlet line with water as much as possible before connecting to the pump to help with the initial prime. As to the high temp...the older Universals had 2 inch heat exchangers which are marginal at best. They need to be removed and cleaned on a regular basis. Another option is to install a 3 inch unit like the 25XPs have. Lenco up here on Long Island is a good source.

[Ken Juul]

The last two posts are great ideas.  I would caution against using petroleum jelly.  I've been told it can soften the rubber leading to blade failure.  I lube the impeller with vegetable or olive oil.  Spray silicone could also be used.

[Steve W10]

I've read that about petroleum jelly as well Ken.

I used to store my impeller coated in PJ in a ziplock bag over winter.  Didn't really have any issues except with longer in the tooth impellers.  A few years back I started (with advice from this forum) storing them with silicone instead.  Not sure it's really that much better, but any better is always good.

I use the PJ just for installation now, and having pulled one out after only a short engine run, was surprised at how there was none left on it.  A thinner product won't give the same initial sealing performance.

Let us know how things work out Jeff.

Steve

[bayates]

Jeff,

My experience on the M25XP on our C-30 was blockage in the heat exchanger. I used the reverse flush with Rydelyme described in Mainsheet to clean it and water was shooting out the back.   I was diligent in replacing the impeller as I had a huge disaster when we first bought the boat.  This fixed my issue. Did it once a year and never had an issue again.

[Jeff Kaplan]

Guys, thanks for the suggestions.  The removed impeller had all its blades.  Both new impellers I installed were put in wet. A new pencil zinc was installed before launch in heat x.  The cover was cleaned and the proper gasket was bought with the impellers.  I just don't know why it is not priming.  One thing I forgot to mention was that I increase the rev's constantly to see if there was an air block and even took the boat out under load to see if this would help, not. Keep the suggestions coming.  Thanks,  Jeff

[n624ma]

Jeff,
Have you tried priming the hose?

Disconnect the inlet hose at the pump, stick a funnel in it and with the sea-cock closed fill it with water, reconnect and do not open the sea-cock until the engine is cranking (you need two people).

I do this ever spring when we launch and have never had a "dry" start. (Yes I,m anal about the engine but I'm an aircraft mechanic and it comes with the territory )

[Jeff Kaplan]

Thanks Joe, I will try that and see what happens...Jeff

[Ron Hill]

Jeff : You can try Joes' suggestion or do the same thing by sucking water into the Oberdoffer by removing the inlet hose, once the water comes out close the thru hull.( 2 people)

Also remove the exit hose from the Oberdoffer and blow into it.  You should be able to blow air in to the hose, thru the HX and into the muffler!!  If not you've got something clogging that route.  I'd guess an old impeller blade(look in the pump brass elbow) or Zn junk in the HX (remove end cap to check)

I''ll guess that you are loosing prime from a worn pump part!   

A few thoughts

[Ed Shankle]

Jeff,
Had a similar problem a couple of years ago and after going through all the steps noted already, I pulled the HX and found a huge growth just inside the raw water intake nipple. It was barnacle like. Basically minimized the opening to about a quarter of the size. Had the HX cleaned and all was well.

Ed

[Jeff Kaplan]

Just wanted to give a follow up as to where I am now. Spoke with Bob Hanson @ Hanson Marine in Marblehead,Ma. and he gave me a few more tests to run, which didn't work, with a follow up of removing the waterpump and heat X
and bringing them to their shop for repair.  As a follow up to Ed and Ron, the heat X was plugged up, so they will boil out and check the h2o pump.  Should be ready by friday so when re-installed I will report back and let you know my outcome.  Thanks for all the suggestions....jeff

[Jeff Kaplan]

Just an update as to the overheating.  Yesterday,picked up heat X and waterpump from Hanson's Marine, heat x boiled out and cleaned, waterpump was rebuilt.  Brought to boat and reinstalled both.  Filled up antifreeze, sucked water thru the intake hose and fired her up.  To my dismay, no water being pumped, now I'm flipping out.  Took off pump cover and installed another impeller, sprayed with silicone and tried again.  After a minute water was flowing, but engine temp climbed, knew I had an air block, no antifreeze moving.  Reworked a few steps and fired her up again.  Water was pumping and the temp went back down and remained constant.  Success finally.  I can now go sailing again.  Moral of the story, never give up till it's fixed, done. Thanks to all....Jeff

[Steve Sayian]

Jeff,

If you ever do decide to upgrade to the 3" HX, Thermaflow in Watertown (617-924-3877) can get a replacement.  I bought one this spring for $480.00.  Factory OEM eq and had it in 3 days.

Steve