2.2 coolant leak

willisbr

Active Member
Joined
Sep 23, 2009
Messages
1,371
Location
Pace, Florida
Aircraft
Maule MT7-235; RAF 2000 (sold)
I have to locate a source of a coolant leak. It's beading around the rear seam of the engine and then drips down on to the engine support. Any idea where I could look first? I have not gone into an engine before. I was told that the water pump may be a first suspect but I wanted to get some more opinions as well. I'll send a pic later when I get home. Thanks.
 
Brian,

Just because the coolant shows at the rear of the engine doesn't mean that's where it's coming from. Airflow could be moving the coolant back to where you're seeing it.

First check the obvious, all the coolant hose fittings. Then the coolant temp sensor. If it's your water pump, you should have coolant on the bottom of the timing belt cover.

My coolant reservoir has a crack in it about halfway up. Found coolant pooled on the top rear of the engine. Took me a while to figure out it was the reservoir, evidently I had filled the reservoir to above the crack in it.

I now run my coolant reserve level so the level shows in the tube going up to the reservoir. That way it's easy to see if I'm losing coolant, and overfilling the reservoir isn't a problem any more.
 
Thanks Mark. There is a class II leak on the bottom of the timing belt cover but its a bit darker, thought maybe it was here. I understand it may not be coming from the rear of the engine. Just that's where it's pooling/beading because of the way the engine sits down in the rear. I'm sure it's coming from somewhere forward and/or up. I'll do some more probing when I get home. Thanks for your help. Any reason there may be a bead of oil on the bottom of the timing belt cover?
 
It probably isn't the water pump, but there are some tubes that go up from it to the throttle body that could be the culprit. A leak up there could easily follow the tubes down and end up almost anywhere. It is most likely leaking on a connection around the throttle body. Lots of little fiddly bits around there that are "re-manufactured" and routed for gyro use.

If you do replace the water pump, do the idler pulleys and the timing belt at the same time. It is a pain, but you'll save money if you buy a kit that has the idlers, water pump, belt tensioner and timing belt. BE VERY CAREFUL to get the timing marks exactly right. The valves you save may be your own.

It isn't smart to replace any of the timing-belt components without replacing them all.
 
If you do replace the water pump, do the idler pulleys and the timing belt at the same time. It is a pain, but you'll save money if you buy a kit that has the idlers, water pump, belt tensioner and timing belt. BE VERY CAREFUL to get the timing marks exactly right. The valves you save may be your own.

It isn't smart to replace any of the timing-belt components without replacing them all.

I want to do this part soon as well. Can I do this myself and would I need to yank the engine off? Don't know if you've had hands on an RAF before. Seems kinda tight back there. I'm at about 260 hours fyi.
 
I did mine...but I had good access to the front of the engine. The nuts and bolts piece isn't so bad as long as you get the belt alignment back right. It changes when you engage the tensioner and the belt straightens completely out. You might be able to see the line-marks with a little mirror on a RAF without removing the engine.

You will need at least enough room for a torque wrench. If you can get the front of the cam cover off (after removing the belts and main pulley), you'll be able to look for the line-up marks and make a decision about whether you have enough room to do the rest.

There are three alignment marks. One for the crank and one for each of the two cams. The procedure is outlined in most of the after-market engine rebuild books and requires no special tools other than a torque wrench.

Compressing the tensioner is a pain, but releasing it once it place is easy, as it is slow to expand. You don't want to use a vice, as it could burst. I used a hydraulic jack and set it up under the hitch of my truck. That way, it pushed the truck up just a little and the weight gradually compressed the tensioner without causing damage. The tensioner is semi-hydraulic and takes about a minute or two to compress enough to insert a keeper pin. I used a tiny drill bit.
 
Thanks Jon. Love that feeling of relief when its explained to me in terms that sounds like a DIY job. I appreciate it. I have the manual...just need to get it out and see where I get. I'll be making an order soon.
 
Brian,

If you loosen the engine mount, the engine should move back enough to work on the timing stuff. It's tight, but you can get things done. Been there twice, so it does work.

I agree with Jon, if you're going in there, replace everything he mentioned. It's so easy to get the gears one tooth off, that you don't want to be in there any more than you have to.
 
Bryan
Get a Subaru engine book for that engine. It'll help emensilly. Take your time, mark the timing marks with a tinny dab of brite paint. Not so bad, again just take your time, you can do it.
 
Oh...and check and recheck and recheck and recheck the marks (count the teeth on the belt too) after you get everything torqued down. Do this BEFORE you turn the crank at all. Getting the cam alignment wrong is a bad day. A little wrong might not bend valves or crack a piston on startup, but a lot wrong will.

Be careful you properly identify the marks on the cam gears. On mine, there are some marks that are highly obvious and look like what you might expect to see, but it is the tiny, hard to see marks that are the right ones. It is a good idea to get all the identification done before disassembly. Marking the bits with a paint marker isn't a bad idea at all. It would pay to take a few minutes before disassembly and get really familiar with what it looks like when properly lined up. Maybe turn the engine over a time or two by hand with the prop and watch it cycle.
 
I found that lining everything up before removing the gears and belt was good. If your careful you should be able to replace all parts and not move anything. Check everything.
 
Here is a video of what I'm seeing. Is this where the water pump is? Can't start it tonight. No lights outside or help. Possible the gadget just needs replaced or is the pump itself suspect? Haven't had any temp problems. Just filled with about a quart of coolant mix to give an idea of how much I lost in about an hour flight. Thanks.

http://www.youtube.com/watch?v=re7N4m6RFgw
 
What is in the part you pointed at in the Video, is the thermostat.

Also look very close where the head meets the Block, Subaru's are known for blown head gaskets.

I know as I have owned 5 Subarus. the Water pump is the part just above the thermostat housing that you pointed to in the Video, it is attached by bolts from the front of the engine. the timing belt will run on a pulley that drives the water pump.

there are several Subaru Forums that discuss the head gasket leaks and even some videos on how to replace the belt.

1998 Subaru Legacy timing belt replacement 1.8 2.2 - YouTube


Subaru timing belt and water pump replacement 2.2L SOHC - YouTube
 
Last edited:
So what do I do now and how do I know for sure? I've never been into an engine before like that. Guidance.
 
you might can find someone local on the Subaru forums that would probably love to help you with it, just for the coolness of helping work on an aircraft. I know on the forester forums there are a few pilots.

http://www.subaruforester.org

maybe offer them a ride for the help.
 
I'm going to pull the thermostat and check the gasket there first. I'm just not sold on the head gasket thing yet since there is no moisture above the oil pan. It all seems to be around the thermostat and water pump. Going to also pull the timing covers and check back there. Out of town this weekend. Will know more Sunday.
 
Hm. Was 1/2 a quart of oil over. Drained it. Haven't had a problem with coolant leak since. Thoughts?
 
Hm. Was 1/2 a quart of oil over. Drained it. Haven't had a problem with coolant leak since. Thoughts?

Was the oil clean or milky? Maybe the water is getting in the oil.
Leaking water is not normal, don't stop looking till ya find it!
Brad
 
Hum, Post 12 says you added coolant and now you need to remove oil… Sounds like you may have multiple problems but I am leaning towards the water pump shaft seal for your leak. It is very common for them to leak at that seal when they are used in aircraft due to almost constant doubling of the RPM it turns so they just do not last as long as they do in a car. I had to replace mine for that same leak you are having, but I was not having the coolant and oil issue.
 
Steve, what I was wondering is if having too much oil would increase oil pressure and somehow affect water pressure. The two may not be related. All I know is that I wiped everthing down the other day so I could do a runup and see if anything leaked. During the wipe down, I checked the oil and decided to drain about 1/2 a quart out. When I did my runup, I saw no coolant wetness anywhere. Then I took a flight. Again, nothing. Then a short CC yesterday...nothing. So I was just wondering if draining the oil may have had anything to do with it. Eben said the same thing you did in a recent email though. To replace the gasket in there.
 
Top