Volvo 2001 cooling problem

"In what would have been our f

"In what would have been our first sail of 2010, while warming up our Volvo 2001 engine in our Beneteau First 265, the overheating alarm sounded for the first time ever. The oil seemed dirty, so I changed it and the filter. The alarm sounded again after the engine had run for about 15 minutes. No cooling water was seen coming out of the hull. I opened the water, before figuring out that I should first close the intake, and learned there was plenty of lake water available. I checked the impeller and it seemed to be in good shape, though I had never seen one before. We turned over the engine to see if the pump shaft rotated and it did not.
I have no diesel experience and would have someone fix it, but there are no marine diesel mechanics here, to my knowledge. I assume that the shaft should rotate whenever the engine is running to circulate cooling water when the thermostat allowed it. Is this correct?
We did not have a hard Winter here and, to my knowledge, we suffered no damage. As overheating points to the cooling system, I thought that I might rebuild the water pump and change the thermostat, to try to cover the likely bases. We would appreciate any thoughts about the cause and how to fix it. Thanks in advance.}"

"I'm not familiar with tha

"I'm not familiar with that engine, but yes, the impeller should turn when the engine is turning. You may get better information here, but I would recommend getting the service manual for your engine if you plan on working on it.

With the service manual, any competent mechanic could diagnose and repair minor problems such as yours.

You don't say where you are, but there are diesel mechanics just about everywhere. Think of diesel cars, diesel trucks, construction equipment, generators, etc. Somebody takes care of them."

It should n't take a diese

It should n't take a diesel mech to help . he impeller has got to turn to circulate the coolant.Is it belt driven or grear driven?

"Thanks to Ronald and Alan for

"Thanks to Ronald and Alan for getting back so quickly and confirming my assumption that the the impeller should spin all of the time. It now seems silly to have not known this.

The pump assembly diagram shows the opposite end of the shaft with a cross pin that looks like a drive pin. It is unclear in what I have to look at what turns the impeller shaft. The shaft end with the pin extends into the engine, far from the one V belt, so I assume the pin fits into a gear with crankshaft output. I wonder if the pin has sheered. The engine runs fine before overheating, so I assume that whatever happened hasn't destroyed major engine components. I say this with fingers tightly crossed.

We live in Little Rock in the middle of Arkansas. Our boat is on a small lake near here and and is not easily trailerable. We have diesel mechanics here, but no one knows of any able and willing to work on small marine diesels at marinas. Of the few sailboats here, only a tiny fraction use diesels, so there is little demand. Owners sometimes hear rumors of mechanics willing to work on them, but the last time I had heard, no one has actually had one come when called. I can check with the few other diesel owners, as this may have changed, but it has been a problem for us. Unfortunately, I think that we will have to fix this mostly by ourselves.

Again, thanks for the responses and any other thoughts you might have."

"Earl ,there is ,should be a h

"Earl ,there is ,should be a half moon key that is between the shaft and the impeller itself that could shear , try to see if the impeller can be turned by hand or it is secured to the shaft? make sure the shaft is not turning inside the impeller while the engine is running"

"What a great resource this is

"What a great resource this is proving to be!

I did not try to rotate the impeller before removing it. The impeller and the half moon key, something I had never heard of until now, looked fine, insofar as I could tell. I found no reason why the impeller would not rotate with the shaft.

When we turned the engine over, with the impeller off, the shaft DID NOT rotate. The shaft turned freely for only about 1/8th turn with a screwdriver in the slot. I did not apply much turning force. I am not familiar with normal friction, etc. within an engine and it might have turned with more force, but I was afraid to damage something. I can try this tomorrow as, believe it or not, I have to work today. }"

"Gentlemen, 2000 series pump i

"Gentlemen, 2000 series pump is driven by a plastic gear from cam. Split pin in shaft allows gear to rotate shaft for impeller. Impeller also has a pin through it to allow rotation. Sounds like gear or pin inside are blown.remove pump to check."

"Richard, thanks for the help.

"Richard, thanks for the help. Purely as a guess, this sounds likely to me.

I wonder how hard it is to replace a blown gear which must be deep within the engine. I have not yet found a diagram that shows this gear that turns the water pump shaft. Someone from the dealer is supposed to call me tomorrow to see if we can figure out what I need."

Richard wins the prize. I don't know what the prize is, but he definitely wins it.
After removing the pump, I found that the plastic gear broken. Perhaps foolishly, I thought that I would use my new water pump overhaul kit to replace all of the parts. They did not seem especially worn, but I am not sure that I would recognize wear and thought that it might save some work in the long run. The assembly of the new pump parts went well until I got to the impeller.
It refused to go into place. The rubber of the old and new impellers is identical, but the internal holes are different. The hole of the new impeller (old # 875583, new # 3586496) is 9mm. The impeller shaft diameter and the hole on the old one are both 12mm. Using an Xacto knife, I cut the brass reinforcements out of both impellers and transplanted the old one to the new one, gluing it in place. After assembling and starting the engine, I checked to see that water was being expelled from the boat. It was oily for a few moments and then ran clear. I thought that I might have a whole new career path as a diesel mechanic until I found water leaking from a large hole in the side of the engine block. The water pumps from the boat and from the hole in the block at the same time.
I found a 35mm round steel engine part below the engine. The parts list shows this is an expansion plug (# 477024). I don't know whether it had come out when it initially overheated or today.
Does anyone know what this part does or what made it come out? It seems to have been pressed into place. It is very hard to get to and harder still to apply any pressure. I thought that I might take some of the edge off and glue it back in place with JB Weld or something similar. I would appreciate any thoughts on this.
Also, I want to replace my modified impeller with a new factory part. This seems less critical at the moment, but does anyone know where to get the proper impeller for a 12mm shaft? Thanks.

Sounds like a freeze plug popped out. Its there to protect your block...should it freeze. And right very hard to get to on nearly all engines, unless it's torn down to a basic block. I'd get the correct impeller and new freeze plugs.

BobT

Thanks for your reply. I wonder why the plug popped out. I doubt that the engine got cold enough for it to freeze as I thought that it had enough warmth during the cold part or our winter. I wonder if something else created pressure in the water channels.

The plug is hard to access, but I do not think it will be impossible. I tried a rubber expansion plug, which would have had to go a half inch into the engine to get a good grip. The interior shape of walls within the hole does not allow this. The plug must be the thin coin shape of the original part. I have ordered some.

The impeller problem is that, assuming that I received the correct part, which replaced the original part number, is that it is not sized to fit on the shaft. The new impeller's hole is 3mm too small. I have ordered another thinking that some error occurred and I was sent a not-to-spec part.

Hi there

Just been reading about the problems your having, firstly there is two reasons why your core plug may have popped out, 1st is due to water in the engine freezing but if the boat was in the water all winter and not dried out then i would find this unlikely. did the lake freeze during the winter, 2nd and could be the cause of your water pump drive gear breaking up is the exhaust elbow exiting the engine corrodes internally causing the water system to pressurize as it cant exit the engine fast anoth, with this happing the water still gets pumped from the water pump and will cause the core plug to pop out or drive gear to break up, possibly take off the exhaust elbow and check the hole where the water enters it and see if blocked. i have seen this happen before, hope this helps, let me know how you get on

After awaiting the arrival of parts, I reassembled the engine and it runs very well, with one exception. There is a leak from where the metal pipe running from the thermostat housing to the exhaust elbow. This is after replacing the seal. I may not have put enough gasket sealant on seal. Rather than disassemble again, I would appreciate a recommendation for a water sealant that could be applied to the outside of where the parts join together. It would obviously need to withstand the temperature of water exiting the thermostat. Thanks for any help.