Genset leaks

[BrianE]

Just discovered our Powertech 17.5 (Kubota) is leaking from 2 freezeplugs. Luckily I have the previous Prevost Mtc invoices and it shows two were replaced in '05. Have a call in to the previous owner to find out why. Spoke to my generator expert at Wrico Intl. and was told the Kubota will not accept generic freeze plugs, they don't fit. Just another "gottcha" to look out for from Prevost Mtc.

Question: Seems like a good time to flush the coolant system. What's the best procedure and flushing product?
Thanks.

[Jon Wehrenberg]

Brian,

I've never flushed the generator cooling system (or bus for that matter except for refilling with water and redraining) but I suspect each generator cooling system is different enough to use different methods.

My experience is limited to Liberty and as you know they have drain plugs on the copper pipes at the low point between the remote radiator and the generator. I drain there and fill at the radiator using a funnel I hang higher than the radiator cap somewhere on the arms of the bay door. I bleed air from the generator by opening the cap on the generator itself.

The Kubota on the first coach was much easier to fill and bleed compared to the Yanmar on this coach. The Yanmar is very difficult for me to burp the air bubbles out of it, although running it for a few minutes and filling at the generator cap seems to do it after about 5 tries. As to why I do not flush (I presume you mean using chemicals) it is because both my generators ran on the cool side. I never had an indication of temperatures beyond 170 to 180.

Why would a soft plug need to be replaced? I'll bet it has been 40 years since I dealt with a freeze plug replacement.

[Joe Cannarozzi]

I treat the coolant in the gen just as the 8-V low silicone with additives and test strips.

[truk4u]

Joe,

Why? They don't have wet liners to they?

[Joe Cannarozzi]

Tom I'm not sure.

[BrianE]

Jon, I've never used a chemical flush either and probably won't unless someone here recommends it. Am also curious about the plug replacement and have a call in to the previous owner of the bus.

Joe, Am not sure if it's a wet sleeve engine. Thought I'd try the brain trust before calling Kubota. Will report back.

[hhoppe]

A little thread creep on a near subject. After a recent coolant drain and re-fill with CDL coolant I had the bus out this past weekend. I ran the webasto for 30-40 minutes on two mornings. When I got ready to head home the dreaded check engine light was on red. I checked oil, transmission fluid and made my way to the engine water holding tank. Luckily I had three gallons of the new antifreeze on board and it took all three to fill the system. Evidently the webasto water system had a huge bubble in it that did not show up until I ran it. We ran the engine on the road after the coolant change and added more fluid. I even ran the webasto for a short spell at that time and the bubble stayed in the system until this later date. All ended well.
Brian I think you have the answer to your Gen Set scoped out. Good Luck.

[Judi Brown]

Our gen. runs to hot and my husband is thinking of putting elec. fan on from 1 of those japan cars. Has any 1 tried this.
JB

[BrianE]

Judi,

Not sure about a '91 but my '94 Liberty had a large electric blower as part of the system. If this blower is installed in your coach, the genset won't run without it running also. Would look elsewhere for overheat problems such as clogged radiator, poor airflow due to dirty vent openings, etc.

[BrianE]

Harry, Had exactly the same experience when I drained and refilled the Liberty with Extended Life Coolant (ELC). There is a small purge valve installed at the high point in the Webasto system. Usually near the driver's AC evaporator, behind the grate at the top of the entrance steps. Running the Webasto with this valve depressed (Schrader) helps but the system still seems to retain a lot of air until the engine has run for awhile.

[Judi Brown]

Brian,
He says he is going to leave that blower fan in and put elec. on other side on thermosat. He also says he wants to replace that elec. pump, as it makes noise and he figures barrings are bad.
JB

[Jon Wehrenberg]

I think this applies to both the generator and engine coolant changes. At least it does for the ones I have worked on.

The key is to get the thermostats open.

I would run the engine and the webasto and get things up to temperature, including raising the thermostat settings in the house so the system was calling for heat which means water coolant circulation. It does a good job of burping. Doing that followed by a 15 mile drive with everything coming up to full operating temperature finishes the job.

When I change the generator coolant I bring it up to operating temperature also otherwise I am trying to get fresh coolant to seep past a closed thermostat and that is tough if not impossible.

Judi,

If the Liberty generator is runing hot, verify the radiator cooling fan is working. If it is, verify the separate coolant circulating pump is actually pumping coolant. The third thing on my list would be to look under the coach and verify the generator steel baffle has not been crushed and blocking air, or is missing. If the baffle is missing it is possible that hot radiator air is being pulled right back through the radiator, and when that happens the cooling fan shuts down due to the thermal switch. Generally the Liberty generator cooling systems are so efficient the reverse is a problem, They have a hard time coming up to temperature which is not good for the engine.