Engine Overheats - Raw Water Problems - Help!

[Masquerade]

I don't know whether I will add to your confusion but I have just spent several days working on a mates boat whose engine was overheating. We checked all the things others have suggested. There was water flowing out the outlet and everything seemed to be doing all the right things but it still overheated. The clue came when we tasted the fresh coolant water. It was salty. We had replaced the gaskets.'O' rings on the heat exchanger, checket the impellor and water pump and the mixing elbow on the exhaust. Nothing made sense.

Mind you the previous owners supposedly paid considerable money to have the problem fixed.

So we pulled the whole lot apart again (there is always one nut that is almost impossible to get to and rips skin off the knuckles when it does loosen). This time the mixing elbow was examined. The outflow of the salt water was completely blocked with carbon. It was blocked so smoothly that it actually looked normal and it wasn't until we really had a close look at it that we found the blockage. It was impossible to scrape it out and in a place that made it impossible to drill out. No alternative but to throw it out and replace it. What we hadn't realised was that the pressure from the salt water pum on the intake was great enough to force the water through the seals on the heat exchanger and into the freshwater side.

What was interesting was that the replacement elbow mixer was totally different in design so we suspect that this might have been a common problem. The manufacturer suggested that it had happened to weekender boats where the motor was only used for a relatvely short time and then cooled down so the carbon deposits built up over time.

Good luch with it and I will be interested to hear how it all works out.
Colin

[Beersmith]

Thanks for the help everyone. Here is my action list for now:

-Find gasket for water strainer, install. My strainer is a Perko strainer, West Marine sells cork gaskets for them and replacement part kits. Is there a better/cheaper option?

-Disconnect the mixing elbow and inspect water flow per Mesquakee's instructions.

-Attempt to remove the impeller again. I will look at a hardware store for the bent needle nose pliers. If they are cheap and they look like they might work, I'll give them a shot.

-If that doesn't work, remove the water pump itself. I'll probably kill myself with frustration trying to do this, but it must be done if I can't get the impeller out otherwise.

-Lube and install new impeller, check cover plate for scoring, replace o-ring.

Originally Posted by JiffyLube

The raw water pump on our Pathfinder is pretty hard to get to also, but I took the time to think this problem out, and went to Sears to get a couple of Craftsman tools just for this challenge. After completely removing and replacing the pump and impeller a couple of times, I'm glad I invested in the special tools to make the job easier. Maybe you need to look at spending some money on pump pulling specific tools.

any advice on removing the pump if it comes to it? What tools did you have to buy.

If I am remembering correctly, the belt doesnt actually turn the pump. So i guess it is gear driven? Does this make things more complicated for me?

[bstreep]

There's a company that makes a quick removal kit for impellers. Since yours is in such an ugly place, I'd invest in it.

Also, REMOVE the impeller. Sometimes the entire outside rubber piece breaks away from the center piece, and it's hard to tell that it's actually bad.

[JiffyLube]

Originally Posted by Beersmith

any advice on removing the pump if it comes to it? What tools did you have to buy.

If I am remembering correctly, the belt doesnt actually turn the pump. So i guess it is gear driven? Does this make things more complicated for me?

I started trying all my wrenches and sockets until I was able to determine what I would need, then went to Sears and hunted for the specific wrenches that would do the job.

Different engines have different pump setups. Some are gear driven, and some are belt driven. My experience is with belt driven pumps only.

[s/v Jedi]

Many engine blocks are Japanese so they use metric fasteners. Most of the time, a standard set of wrenches and sockets (metric) is all you need. If there's not enough room for the wrench you can cut the wrench shorter.

A gear driven pump is easy: undo the bolts and pull it out. You will have to pull the gear off the pump shaft and mount it on the new pump, so you will need a gear puller.

Don't worry about oil coming out: it will all be down in the sump.

cheers,
Nick.

[JiffyLube]

Originally Posted by Beersmith

Thanks for the help everyone. Here is my action list for now:

-Find gasket for water strainer, install. My strainer is a Perko strainer, West Marine sells cork gaskets for them and replacement part kits. Is there a better/cheaper option?

-Disconnect the mixing elbow and inspect water flow per Mesquakee's instructions.

-Attempt to remove the impeller again. I will look at a hardware store for the bent needle nose pliers. If they are cheap and they look like they might work, I'll give them a shot.

-If that doesn't work, remove the water pump itself. I'll probably kill myself with frustration trying to do this, but it must be done if I can't get the impeller out otherwise.

-Lube and install new impeller, check cover plate for scoring, replace o-ring.



any advice on removing the pump if it comes to it? What tools did you have to buy.

If I am remembering correctly, the belt doesnt actually turn the pump. So i guess it is gear driven? Does this make things more complicated for me?

In my case I needed to find short wrenches to loosen the two nuts holding the pump (sockets would not work), and once I got one nut and bolt out I was able to turn the pump enough to get the belt off, then removing the other nut and bolt was easy. Putting the pump back on required reversing the order of the nut and bolt installation. The belts on the engine and the limited working space around the engine, made the removal and replacement process the hard part. Sometimes a person just needs to think this removal process out, and with the right tool for the job it can be done.

[s/v Geneve]

Originally Posted by Beersmith

-Attempt to remove the impeller again. I will look at a hardware store for the bent needle nose pliers. If they are cheap and they look like they might work, I'll give them a shot.

any advice on removing the pump if it comes to it? What tools did you have to buy.

If your looking for a cheap solution for tools that you don't want to buy now, almost every auto parts store in my area has a tool loaner program. They either let you use tools they have in house or you buy the one you need, use it, then they let you return it for a full refund. I've used this several times for odd tools that you don't use much, or if you need the cash for other projects.

[Beersmith]

Update on the problem:

This weekend I finally was able to get back to the boat and check out the engine problem again. First, I went over the side of the boat and made sure the though hull wasn't blocked. I also blew out the hose coming from the through hull just in case. I then cranked the engine to make sure there were no leaky or collapsing hoses. I then removed the hose that comes out of the heat exchanger into the vented loop to see if water was coming out when the engine was cranked, nothing. So then I removed the cover of the pump to see the impeller, and when the engine was cranked I saw that the impeller was not spinning at all.

So the problem lies directly on the water pump and the impeller not spinning. Is this a totally busted pump or just some component in the pump that fails, perhaps the shaft? I guess my only option now is to take apart the water pump and figure it out from there? Any ideas?

[imagine2frolic]

Most likely you only need the impeller. Could you see the shaft spinning? If so just an impeller will do, and get an extra. It can be a common problem.......i2f

[fareweather]

Ya mon, pull that thing out and if it's your lucky day the center will spin independently of the outside. 24$ (+/-)for a new impeller and you're back in business.

If not pull your raw water pump and do some investigating.

[forsailbyowner]

While you're servicing the cooling system you probably should clean out the heat exchanger and check the zinc. Failure to keep a healthy zinc could cost the price of heat exchanger. Their usually cleaned by rodding out the passages with a wooden dowel of correct size. I've found it easy and practical to inspect internals and rebuild the raw water pump on an annual basis.

[Beersmith]

Thanks to everyone for helping me out with this problem! I finally got the impeller removed and replaced and got the flow to the engine again. It took many times trying, since the impeller was STUCK onto the hub after years of non-use and no maintenance.

Thanks a ton for the help and motivation.

[shakey doug]

If possible it is so much easier if you can remove pump if not get a couple of cheap screw drivers and bend the ends 90degs. Seems you have taken care of the suction side ,remove hose from heat exchanger end using a piece of wire fish any impeller parts that have lodged there out---Patience. I replace a lot of impellers [work`] occasionally i have had a impeller centre turning in the drive boss looks perfect--BUT.Depenps on your filter make as to the sealing type look around the rim for a relief for a joint or 'o' ring . Use a bit of honey moon starters on a new impeller to aviod dry start problems ----Remember? The pump will prime in about 12-20 seconds if the circuit is as it should be.