RAF EJ22 Engine Coolant Pressure

[Hoges]

I recently fitted a coolant pressure gauge to my RAF and made the mistake of fitting the sensor on the heater return hose which enters the thermostat housing.
This is on the intake side of the water pump.
With the engine warmed and the thermostat opened and at idle, the coolant pressure was about 8-10 PSI.
As the engine revs were increased to 5,100 RPM the pressure dropped to zero.
My gauge doesn't read a negative pressure.
I'm wondering if this was the inexplicable cause of the failure of my water pump shaft seal at about 180 hours?
Are these seals designed to seal at zero or negative pressures?
I don't think many car engines would be run at those kind of revs for long.
I have since fitted the sensor just below the radiator cap and get a more even reading.
Hoges
________
New Mexico Dispensaries (http://newmexico.dispensaries.org/)

[Steve Osborne]

Were you having a problem prior to installing the pressure gauge? It is very common for the water pumps in soobs to go bad. Normally you will notice overheating on the temp gauge or a leak at the WP shaft seal. If you were not having a problem prior, it may just be air in the system from the gauge installation.. Make sure you always have fluid in the clear hose running from the rad cap to the expansion tank. Best time to check it is when the motor is cold. If you do not have fluid in this hose when cold it is possible for air to enter the system and cause cavitation resulting in a pump failure
Squeeze the lower rad hose with both hands several times, listen for any sloshing in the rad, (should be none) then go up to the rad cap filler neck and wiggle it back and forth, then tap on the cap with 2 fingers. Look to see if you have any air bubbles working there way up threw the clear hose. Once you are confident there is no air in the system and if you are still having a problem, replace the pump and thermostat with new soob parts, not aftermarket. Hope this helps.

[Aussie_Paul]

The Soob mechanics book says to fill the radiator while squeezing the hoses etc like Steve suggested. Start the engine and run for 5 mins at 2000 engine rpm. This allow's the thermostat to open. Turn the engine off and go have a cup of coffee or do another job for 30 mins. After that refil the radiator and 1/2 fill the over flow tank. That is supposed to get rid of the air lock problem. :)

My radiator guy says that Soobs are the worst veichle he for air locks. Some engines are fine and others it is a hell of a job to get all the air out.

At one time I removed the thermostat and bolted 2 thermostat housings together to fit the thermostat after the water came out of the engine. That was terrific. I never had an air problem after replacing the coolant.

Maybe I should get some in line thermostat housings made to fit after the hot water comes out of the engine.

Aussie Paul :)

[OzyRuss]

Drilling a 1/4" hole in the thermostate plate helps heaps. Aids the removal of trapped air there. Also allows cycling of water / air when therm is closed.

[OzyRuss]

Me new ej25 with box attached

[Aussie_Paul]

Me new ej25 with box attached

My ej-25 Russ. :p

Aussie Paul. :)

[OzyRuss]

2 new "Raftorrs" getting completed. Both near identical.

[OzyRuss]

Winners are grinners

[Hoges]

Yes Steve, I had a forced landing as a result of a radiator cap failure.
The cap didn't seal completely and after a while the engine temp increased and suddenly went off the dial.
We were then in 'glide mode'.
Luckily, I was watching the temp gauge as it was reading a little higher than normal and we moved to a more 'friendly' area in case we had to land.
After this experience, I spoke to a few different pilots and found that mustering pilots had coolant and fuel pressure gauges fitted on their EJ22's for these very reasons.
Good enough for me too!
Now I have gauges and nothing to compare to from before.
I found that the coolant pressure increases with engine revs, especially 2 up with a lot of power all the time.
I don't think the water pump was ever designed to run at 90% max revs all the time.
The EFI fuel gauge sits at about 32 PSI and increases as engine revs increase and then settles back a bit. It's a great way to tell if you have any fuel leaks in your high pressure side after your aircraft has sat for a week in the hangar.
Thanks for the input.
Hoges
________
Universal health (http://uhwh.com/)

[Harry_S.]

Your machines are lookin' good, Russ. Won't be long now. ;)

I operate a bit differently than most. I put two 1/8" holes in the thermo flange to help any air or water transfer problems. When I change new coolant, I fill slowly and when the level gets thru the water jacket, I stop and squeeze pump the rad hose going to the thermo a few times. Add coolant to one inch below the top of the stand-up and squeeze the hose again. When no more bubbles come to the surface, I secure the rad cap and run the engine for 2-3 min.

Shut the engine down and remove the rad cap and squeeze the hose till no more bubbles. Add coolant if needed and run the engine again. Add coolant till it reaches the tank hose and secure the rad cap.

I do not put any coolant in the surge tank. I remove the rad cap on every pre-flight and make sure the coolant level is to the hose opening. The surge tank hose is empty at pre-flight but is full of coolant after a flight, which indicates the pressure system is working.


Cheers :)

[Aussie_Paul]

Your machines are lookin' good, Russ. Won't be long now. ;)

I do not put any coolant in the surge tank. I remove the rad cap on every pre-flight and make sure the coolant level is to the hose opening. The surge tank hose is empty at pre-flight but is full of coolant after a flight, which indicates the pressure system is working.


Cheers :)

Good system Harry.:first:

Aussie Paul. :)

[OzyRuss]

if me coolant bottle was empty pre flite...........and "full" after flite, i would be thinkin.....sumin wrong. Would be thinkin of more, better heat control.

Always ran the top bottle 1/3rd full.........when cold, rises a tad after flite, then sucks back as she cools off........back to 1/3rd. To me that is the way it spozed to be.

And another thing...........too much of that "coolant" additive stuff, actually does the opposite........makes things hotter. The ratio of water / additive is important, as is the "brand" of coolant used. Some are useless.

[Harry_S.]

[QUOTE=OzyRuss;166469]if me coolant bottle was empty pre flite...........and "full" after flite, i would be thinkin.....sumin wrong. Would be thinkin of more, better heat control.

Always ran the top bottle 1/3rd full.........when cold, rises a tad after flite, then sucks back as she cools off........back to 1/3rd. To me that is the way it spozed to be.

[QUOTE]



Russ,

The coolant tank and hose are empty at pre-flight. After flight I would not know how much coolant...but I would suspect very little...is in the tank but the "hose" is full. When the engine cools, the coolant that was in the "hose" drains back into the pipe.

If I remember, I will remove the tank plug and slide a stick to the bottom of the tank and just see how much coolant was forced into the tank. I don't think it will be more than maybe a half pint in the hose and tank.

I'll let you know. Oh, and how much do you think is in the "tad" you mentioned above?!


Cheers :)

[OzyRuss]

"Tad".............this term like many others we got here.....eg

poofteenth
just a whisker
a touch more
bout a tallyho paper


these and some others i can't recall at the minute, are seriously precise amounts
not to be jeered at..........we is talkin serious stuff here;)

[Steve Osborne]

That might work in warmer climates, here we have summers temps 95 then in the winter as low 8 this year. In the summer I always see the fluid in the hose up to the tank, cold. In the winter the level will drop to about a 1/4" past the cap. If I filled only to the cap in the summer it would more then likely fall below the water manifold in the winter. :noidea:

[Hoges]

I have also fitted a sight gauge to my coolant reservoir on the mast. After 45 minutes of flight 2 up, there's about 150ml of coolant force out.
In the RAF manual they tell you to fill the reservoir to about one third with coolant once you have remove all the air etc.
I'm with you Steve, I like to fill the system to the underside of the radiator cap so I can check it at preflight.
Scott Hogan
________
CBR125RR (http://www.honda-wiki.org/wiki/Honda_CBR125RR)

[StanFoster]

My system must be the odd ball one. I started flying my SparrowHawk last spring...filled up the reservoir 1/3 rd...had the air all worked out...and it would spout out the top like a whale. I then installed an overflow hose down to my left wheel where I could look out the door and see any coolant going overboard. It was handy that I didnt have all that anti-freeze blowing over.

I checked for coolant leaks with pressure..inside the cylinders for hours...no pressure drop and not a drop of water in the cylinders. I was almost certain that was my problem.

Long story short....If I put ANY in that reservoir...it gets blown overboard. Once I quit adding water.....my overflow never blows over. Its been 6 months now. I think with my heater core and large radiator, every system is a little different.

All I know is I was trying for 6 months to fix a problem I did not have.


Stan

[Gary_in_Orygun]

I like to fill my system where the fluid level is just visible in the clear tube that leads to the reservoir. Although, this time I added a little too much and I can't tell if that clear line is full or empty. I can look over my shoulder out the top window to see that tube in the air.

[Harry_S.]

OzyRuss;

Had a real nice fly today...won't mention the winds, as some people don't believe we have winds here in Florida. ;) :D

Anyway, after returning to the hangar, I got on the ladder to check the fluid level in the surge tank. Laying the dipper along the outside of the tank, the fluid level appeared to be around the bottom edge of the hose fitting, indicating that the fluid forced out of the engine was of an amount to only fill the hose running from the rad cap to the tank. Maybe a TAD more. ;)

I don't know as to how much fluid would be contained in 24" of 3/8" vinyl hose, but it isn't very much. If I had another 24" of hose, I would fill it and MT it out for a measure.

The only reason I see to have additional coolant in the surge tank is to facilitate not having to check the coolant level. Being as I remove the rad cap and check the coolant level on every preflight anyway, I see no need to have extra coolant in the tank. The hose being full of coolant after flight, verifies the pressure system is functioning.

May I add a point here...if anyone ever removes that surge tank from the mast, be forewarned, cover your rear windscreen and be extra careful in removig the tank as there is a bit of residual coolant BELOW that hose fitting and will easily flow out if you're not careful.


Cheers :)