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Perkins coolant drain

Chip

New Member
I want to replace the thermostat in my Lowline 4-108, which has the aft heat exchanger and header tank in the front, and need to drain the coolant. Based on previous threads, I assume the pictured valve below the starboard side drain.jpg fuel pump is the way to do it, but it is stuck tight and I don't want to break anything, due to the horrible access. The hose coming toward the camera is just a short stub, and there may be (I can't see it well) a nipple underneath the "valve." Can anyone suggest a reasonable way to proceed?
 

moltzvt

David Moulton
Ken's suggestion is a good one. I would spray the valve with a penetrating oil such as PB blaster and let it soak for future needs. Consider picking up some new vinyl hose to replace the drain line. I have clear vinyl, it was what was in place when I bought, helps to see whats flowing and when it stops. Keep attempting to wiggle the valve, I used a small closed end wrench that fits over the small rod. Be cautious about over exerting the force used. Your correct in not wanting to snap it off. I found that once the rod was in line with the hose the valve was fully open, so 1/4 turn is all that is necessary. Consider changing the small hose section if needed on the header tank when you have it off. The photo is what you will find once the tank is removed, the header is also removed in this pic.

Good luck.
 

Attachments

wild382

John
Ken's suggestion is a good one. I would spray the valve with a penetrating oil such as PB blaster and let it soak for future needs. Consider picking up some new vinyl hose to replace the drain line. I have clear vinyl, it was what was in place when I bought, helps to see whats flowing and when it stops. Keep attempting to wiggle the valve, I used a small closed end wrench that fits over the small rod. Be cautious about over exerting the force used. Your correct in not wanting to snap it off. I found that once the rod was in line with the hose the valve was fully open, so 1/4 turn is all that is necessary. Consider changing the small hose section if needed on the header tank when you have it off. The photo is what you will find once the tank is removed, the header is also removed in this pic.

Good luck.
David...do you know where the temp gauge wire or connection is on the engine that runs to the gauge?
 

moltzvt

David Moulton
John, In the photo above the temperature sending unit is shown right above the upper bolt in the photo by the thermostat. The wire is actually pulled off in the photo, enlarge the pic, it sits on a fitting. This one has been replaced, no blue paint on it.
 

terry_thatcher

Terence Thatcher
I would cut some access to the drain through the for-aft bulkhead so you can get to it. Brewer designed better access than Morgan provided. You can trim the enlarged access with teak and screw it back in place and it will look fine.
My drain leaked. And so I removed the stupid little thing and put a hose on a nipple where the drain was. I plug the hose and coil it up most of the time, but can unscrew the plug and drain the system when necessary.
 

Cardo

Member
I was attempting to remove my header tank to change the thermostat. No trouble getting the nut off the stud, but the through bolt does not want to turn. I am concerned about breaking the bolt. I have a couple of header tank questions that I was hoping you guys would be able to shed light on:
1. Are both the stud and through-bolt very tight fits throught the tank or could they have corroded to their sleeves through the tank?
2. There is a small pipe that connects from the exhaust manifold to the header tank. What is its purpose?
3. On the bottom of the header tank there is a circular plate bolted on. Is for cleanout access or does it cover some internal baffle or something else?
4. Could I use a shop vac on one of the disconnected hoses at the heat exchanger to drain the coolant?
 

Cardo

Member
I was quite pleased with the shop vac result as it drained all the way through the water heater. I chickened out on removing the header tank at least until next haul out. My assumption is that the small pipe allows air pockets to pass through to the header tank before the thermostat opens as it is a high point in the system. The circular plate shall remain a mystery unless someone knows or until I brave the removal of the header tank in the Fall.
 

rickdowe2

Richard Dowe
Hi Cardo, if your Perkins is like mine with the coolant tank athwart the stud runs through a sleeve not sure about the bolt. The stud/sleeve does corrode but once clean it has a fair amount of space. The plate on the bottom is just a plate. Like you I believe the small tubing is for venting any air in the exhaust.
 

Cardo

Member
Hi Richard, thanks for the help. My Perkins was running a little hot at about 2000 rpms, but as soon as I backed off down to 1800, it was fine again. The raw water reinforced hose had a kink in it that closed the hose up to half its diameter which would significantly reduce flow of water. I have replaced the hose and hope that makes the difference at higher rpms. Thanks again for the help regarding the header tank.
 

dave_a

Dave Ahlers
Cardo, there is a water temp sensor at the back of the head just aft of the valve cover. When you refill you may (will?) need to open that hole to allow air to escape to completely fill the system. My Perk would over heat until that was bled out after refilling with coolant.
If your engine still runs hot, you should take off the ends of the heat exchanger and see what's blocking flow through the tubes. Old impeller blades sometimes wind up there and years of other deposits.
 

Cardo

Member
Thanks, Dave. I have had the ends off the heat exchanger and cleaned each tube with a dowel. The zinc had deteriorated into a small pile which I removed and then replaced. I will remember your bleeding suggestion when I refill the coolant. Thanks again.
 

Cardo

Member
Including the run to the water heater under the sink area in the galley, would the coolant capacity be close to 2 gallons?
 

Travis

Member
Including the run to the water heater under the sink area in the galley, would the coolant capacity be close to 2 gallons?
Hose lengths and diameters can drastically affect this measurement but 2 gallons is what is in the manual.
3EE88ADD-1AB0-41C6-AF77-B64ACD49FD55.jpeg
 

Cardo

Member
I found an older post refering to burping the coolant system. Can the system be "burped" by running the engine with the cap off the header tank and topping up coolant as you go?
 

rickdowe2

Richard Dowe
Hi Cardo, I think my engine design is like yours with the coolant holding tank athwart. If it is the same the sensor you need to remove is slightly under the tank making it difficult to get a wrench or socket on. After thinking for a while and needing to burp the engine I took a socket and with a grinder I cut away a quarter section of it. That allowed me to remove and install the sensor one flat at a time without removing the tank.
IMG_1650.JPG
 
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