thenudehamster

H-6 Losing coolant

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Outback H6, 2003, 120k

 

I've had the car for about 6 months and apart from a rear brake rebuild, had no troubles - until yesterday. Coming back from Tesco the 'VDCOFF' warning light came up and the aircon stopped. I'm guessing now that it was also running hot, but I never thought to check the temp gauge (yes I know I should have done the regular scan, but...) Got home, checked it over, found some loss of coolant, but no obvious cause. Top up, run up, seems OK. Quick trip to the same shopping centre this morning; VDC light on in less than half a mile, and temp climbing quickly. Looks like I'm not going to the Hawk Conservancy today...

 

I've checked it over and I cannot find the source of the coolant loss. There was a steady drip from the back of the undertray, so I took that off and the drip transferred to the cross-member. It seems to be running down the n/s engine mount, but I can't find where from. I traced the coolant pipework and the most likely place seems to be the heater return pipe - not the hose, but the rigid pipe which runs from the hose, has a tapping for the throttle body heater return hose, then goes back to the block through a small straight hose near the bottom rad hose. Aha, thought I; I can solder that up once it's off the car. So, I disconnected it, removed the mounting bolts - and I cannot for the life of me see how to get it out without removing the engine - or at least the n/s engine mount, valve cover, and possibly the l/h head. For all that it feels sound - no serious corrosion or damage, so it cleaned the ends as best I could and refitted it. The leak is still there - but all joints are dry; although I can't see the full length of the pipe, there is a suggestion of dampness along the hidden part, but I cannot see where the drip originates, there's too much 'stuff' in the way. If I could get the pipe off, even if it were not repairable I could jury rig a tee-piece and a hose to replace it, but there's no room at the engine end with it in place.

 

As my nearest dealers are at least forty miles away, I'm a little restricted...

Any ideas? Either alternative possibilities for the source of the leak or ideas to remove the pipe...

 

As a 'by the way' where can I get a shop manual for this car? Haynes have never even heard of Subaru...

 

Regards

 

 

Barry

(thenudehamster)

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Thanks for trying; I found that one myself the other day but that manual is for US-spec vehicles, and specifically says it doesn't cover 6-cylinder models. I have found a couple of ads on ebay offering manuals on CD, so I've ordered one of those; I'll see what it's like in a day or two. Despite being pretty techno-savvy, though, I still prefer to hold a real book.

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On the radiator is the coolant expansion tank, to the right of the rad cap. It has a yellow plastic cap.

Make sure the coolant is topped up to normal levels. In the expansion tank, that's quite low. It has a mark on the outside of the tank.

Go for a drive. As soon as the temp starts to rise above the normal, pull over and open the bonnet. Pull the yellow lid off the expansion tank.

If you can see a obviously raised level of coolant and its bubbling, it's worth going to a garage and getting a sniff test done. It's possible the head gaskets have gone and the sniff test detects combustion gasses in the coolant if they have (generally, Subarus don't mix their oil with water when the gaskets go)

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Thanks Tlag for the suggestion, but I've done the usual non-instrument related checks for a CHG problem (I was an AA Patrol for over twenty years...) including a basic olfactory sniff test (using the Mk1 nose). It's rare on almost any engine for a CHG to leak coolant externally from the engine - they overheat through cylinder gases entering the water jacket and usually leak coolant into the cylinders if it can't get into the oil. Usually gas pressure forces the coolant out of the overflow.

Mine is definitely losing coolant from the aft end of the left hand cylinder bank area - constantly, even with the engine off (it drips onto the n/s engine mount, then runs down and drips off the crossmember) but I haven't been able to see well enough where it's coming from. As I said in the original post, I suspect the rigid heater return pipe, but I can't get the damned thing off to examine it properly. 

Come Saturday I'm going to try releasing the n/s engine mount and jacking the engine up to give me some more clearance, and see how that goes. I might even be able to see some more then, too....

 

I'll keep you guys updated.

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to be honest I've never seen a 6cyl boxer engine but , I'd assume that they'd be some similarities between that and a 4cyl turbo .

Are you sure you've disconnected any sensor wires or cable ties for the engine loom that might be restricting the pipes movement .

Maybe this pic of a 2ltr with the inlet off will help you work out its route

post-1399-140977315261_thumb.jpg

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The only thing restricting movement of the pipe is its shape and location. I can unbolt it, remove all three hoses, and it rattles loose - but there is not enough clearance between the head and the cross-member to get it out, owing to the complex shape of the pipe. I'll get into it again at the weekend and try some other things to get better vision and access. 

Thanks for the thought, though; I'll update as I find out more.

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On 9/4/2014 at 5:06 AM, thenudehamster said:

The only thing restricting movement of the pipe is its shape and location. I can unbolt it, remove all three hoses, and it rattles loose - but there is not enough clearance between the head and the cross-member to get it out, owing to the complex shape of the pipe. I'll get into it again at the weekend and try some other things to get better vision and access. 

Thanks for the thought, though; I'll update as I find out more.

Sorry to resurrect such an old thread, but did you ever get to the bottom of this?. I've got a 3.0 RN which needs continual coolant top-ups after a (low mileage, pressure tested) engine swap. And I can't work out where it's going....

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