Universal 5432 Engine Running Temperature

1. If your coolant cap is higher than the water heater it bleeds automatically. Just keep the coolant topped off.

2. Sure, why not.

3. Propeller might matter here. I need 2300 rpms to get to top speed, about 7 knots in flat water, with my fixed three-bladed prop. WOT is 2600-2700, makes more noise but the stern squats and no speed increase. How fast do you go at 2000 rpms? That sounds like not using allt he diesel has to offer.

I'm not an expert on this stuff.

By the way, no coolant ever shows in my overflow tank. It is "supposed to", or at least that's why the tank is there--so expanded coolant can boil off and then return to the manifold automatically as the engine cools. I guess the point is, individual symptoms don;t always mean the same thing.

Christian Williams said:

1. If your coolant cap is higher than the water heater it bleeds automatically. Just keep the coolant topped off.

2. Sure, why not.

3. Propeller might matter here. I need 2300 rpms to get to top speed, about 7 knots in flat water, with my fixed three-bladed prop. WOT is 2600-2700, makes more noise but the stern squats and no speed increase. How fast do you go at 2000 rpms? That sounds like not using allt he diesel has to offer.

I'm not an expert on this stuff.

By the way, no coolant ever shows in my overflow tank. It is "supposed to", or at least that's why the tank is there--so expanded coolant can boil off and then return to the manifold automatically as the engine cools. I guess the point is, individual symptoms don;t always mean the same thing.

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Thx Christian. That’s just it—-getting all she has to offer. I get 6 or so at 2000 and I can see there’s another knot to go when I push more but not really interested in eying the temp gauge all day. Better things to look at. I do have the original 2 blade. Looking at a max 3 but pricy. Maybe fix 3 is a good idea

Doug

Hi Doug,

I don't know if this will help, but the cooling systems on these engines can be frustrating, especially if there is a hot water tank as well. I had trouble with the engine overheating occasionally without warning after running perfectly for quite a while, despite a good impeller, newer coolant, a clean heat exchanger, good hoses, new thermostat--so what was going on?

My system consists of a freshwater cooled engine, a plastic overflow tank that is half full (level stays constant), a black aluminum box filled with coolant to one inch below the opening, which has a pressure cap on it, and a hot water tank which sits below both the plastic and the aluminum tank (which is higher than the engine itself).

I had heard and read that any air bubbles will disperse in the aluminum tank cause it's the highest point in the system, but on our boat that's not the case. I learned that I need to bleed off a little air at a valve on the engine near the thermostat about every 20 engine hours to prevent overheating and maintain normal consistent engine temperature. Don't ask me why this is, it just is.

If I bleed that air off periodically, the engine runs perfectly at constant temperature and has done so now for a long time. So if you're having overheating or temperature inconsistency, try removing the cap from that overflow and aluminum tank (with engine off and cold), then bleed a bit of air until clear coolant without bubbles is visible if you have a valve at the high point in the system near thermostat (if not, install one), and that may solve the problem. Have a paper towel handy to catch the few drops of coolant and don't forget to replace the cap on the aluminum tank when you're done!

Frank

In case it is an airlock....

Doug,

As Frank has suggested, perhaps you have an airlock somewhere in the system.

Below is the procedure I used on my previous Catalina 30 with a Universal M25XP fresh water cooled engine. I did not have an expansion tank but did have a water heater. I don't know how your engine model is plumbed exactly but perhaps some of what I outline below could be adapted. Using this method I was certain to get all of the air out of the system and did not have overheating problems.

*******

FROM A PREVIOUS POST ON THE CATALINA 30 LIST:

I thought it might be helpful to mention a way to avoid airlock (and hence overheating) when you replace the coolant:

Take off the 3/8” hose at the bottom of the thermostat housing. (This is the hose that goes to the water heater.) You then refill the system through this hose. The best way is to get one of those hand pumps like this: https://www.westmarine.com/buy/camco--hand-pump-winterizing-kit--329179?recordNum=23

You can probably find an even cheaper one of these at Harbor Freight that might do the job for you.

Pump the coolant through the system until it fills up the manifold and starts coming out the hose nipple at the bottom of the thermostat housing, i.e., the nipple from which you just removed the hose. You might want to position a cup or something to catch the overflow. Then remove the 3/8” hose from the hand pump and reconnect it to the thermostat housing. You should not have any airlock at this point.

If you don’t have a pump you can accomplish the job by raising the 3/8” hose as high as possible and filling it through a funnel, letting gravity do the work. I was able to do it successfully using this method but it was very slow, whereas the hand pump will do it lickety split.

I highly recommend this method as sometimes it can be quite an ordeal getting a stubborn airlock out of the system.



Alan Gomes
"Sola Scriptura"
1987 MK-II (#4928), SRFK, M25XP
San Pedro, California

Thx Frank and Alan—-there is a bleed valve on top of the thermostat on my engine —-actually has a wire sensor connected to top of it ?(below) —-pretty confusing I assume the bleeding should be done with the engine running? Also I do not have an aluminum tank but a plastic tank connected via a tube from the top of the manifold by the cap—-the expansion tank I guess. It has a fill line with a screw cap and a small valve on top. This is what was previously filled to the line and now barely shows coolant per my previous post. This plastic tank sits well above the WH and the engine

Thx

Doug

Doug,

The part in your picture that has the wire attached is the temperature warning sensor, not the bleed valve--it reacts to increased coolant temperature by sending a signal to the warning buzzer that's usually in the engine panel area. I didn't see the valve in your picture, but it may be hidden behind other parts. A bleed valve should just turn by hand to release air bubbles.

I used to bleed the air in the coolant with the engine running, but a mechanic told me to do it with the engine off and cold. I tried that, and it seemed to work better and was easier as it wasn't under pressure and I could do it whenever at my leisure.

Frank

Frank Langer said:

Doug,

The part in your picture that has the wire attached is the temperature warning sensor, not the bleed valve--it reacts to increased coolant temperature by sending a signal to the warning buzzer that's usually in the engine panel area. I didn't see the valve in your picture, but it may be hidden behind other parts. A bleed valve should just turn by hand to release air bubbles.

I used to bleed the air in the coolant with the engine running, but a mechanic told me to do it with the engine off and cold. I tried that, and it seemed to work better and was easier as it wasn't under pressure and I could do it whenever at my leisure.

Frank

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Thank you, I like the idea of doing this with the engine off. I do know there is a bleed valve labeled on the westerbeke schematic so I’ll ID it eventually

Doug

Good luck with this, Doug. I hope you can figure it out. I'm not a mechanic, so just sharing my own knowledge gained from my experience owning boats for 25 years, 12 of them my current Ericson. I've explored every nook and cranny in our boat, have read alot and scratched my head while problem solving. If that saves you some time and solves a problem, it's worth it.
Frank

Frank Langer said:

Doug,

The part in your picture that has the wire attached is the temperature warning sensor, not the bleed valve--it reacts to increased coolant temperature by sending a signal to the warning buzzer that's usually in the engine panel area. I didn't see the valve in your picture, but it may be hidden behind other parts. A bleed valve should just turn by hand to release air bubbles.

I used to bleed the air in the coolant with the engine running, but a mechanic told me to do it with the engine off and cold. I tried that, and it seemed to work better and was easier as it wasn't under pressure and I could do it whenever at my leisure.

Frank

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With my M25XP I sometimes found that the bleed valve was not enough to get out the bubble, depending on where in the circuit it was lodged. The method I described, which I used when changing the coolant, forces out any trapped air and was more reliable. But the bleed valve will certainly work some of the time. After you have located and opened the bleed valve, revving/goosing the engine with short bursts of throttle can help move the bubble along.

M-40?

Hi Doug,
It looks like you have an M-40, which makes very little difference to this discussion. There are configuration differences from the 5432 as it is the next step newer block design from Kubota. Do you have a Sherwood raw water pump? Is there a seawater strainer?

The heat exchanger has a pencil zinc which needs to be replaced about twice a year. The fitting is on the rear left of the heat exchanger (port side of the boat). The pencil zinc you buy may need to be cut shorter to fit in the HX. Depends on the manufacturer. It is hard to see but it can be reached and R&R'd while in place. That end of the HX should be raw water only. Removing the port side end cap, and using a mirror, will allow you to check for condition and to clean out any old zinc debris. Flushing the raw water side can be done in place. Let me know if you want to discuss the details. I have some Unchloric acid left from my work.

I also have some engine flush solution (Fleetguard) leftover from my recent experience that I will let you use if you decide to flush the internal coolant passages during your troubleshooting.

You could have a problem with the water heater being a restriction if it is old and has corroded coolant lines. I'd like to see a picture of the hoses on top of the engine. My water heater is plumbed in from the back of the engine rather than from the thermostat area, so both configurations are likely workable.

While it is correct that the water heater will self bleed if it is below the cap, on mine it does take some time with the engine running and maybe a few hours of gentle rocking (after shutdown) for the air to work it's way out. Coolant line routing to the water heater can have an effect on that, I bet. Always check your coolant level the next day after messing with the cooling system!

Beautiful sunset picture!

Pat C. said:

Doug I love the picture, beautiful boat and proud owner...A good combination.

I've read this thread with some interest as I just replumbed my coolant system. I noticed you said the coolant was green. All the diesel coolants I've seen are not but I haven't seen them all so I may be wrong, but... If the PO filled with automotive Prestone without draining all the diesel coolant that could be the problem. Automotive and diesel coolants are not compatible, when mixed they form a gel like consistency that can cause overheating with that gel around the cylinder liners (don't ask me how I know this). Flush the coolant system and refill with diesel coolant, then see what happens.

I've had to get broken zincs out of my HE before, the end where the zinc goes on mine isn't removable so it's a real pain. That could certainly be the issue too.

As far as the engine cutting out, it wouldn't do that at 205-210 even with a safety shut off, which I don't think it has. I would replace my fuel filters for that concern. And temps in the low 200's wouldn't have caused any harm, so no worries. Best of luck.​

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thank you for that, I have contacted PO and it is automotive----not sure if Prestone but I'll check

Doug

I just mentioned Prestone since it's the first thing I think when I see green coolant, any automotive antifreeze is incompatable with diesel coolant.

Pat C. said:

I just mentioned Prestone since it's the first thing I think when I see green coolant, any automotive antifreeze is incompatable with diesel coolant.

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Fortunately I have access to PO. He says was green when he took ownership
in mid 2000s. He changed coolant—-kept using green —-every 3 to 4 years and did with good flush. Unknown how switchbwas made prior to that.

doug