Subaru engine strip down

[David Morris]

Hi All,

I watched an interesting video on You Tube on stripping down a flat four Subaru engine the other night. Lots of similarities to the Javelin engine and, even, some things that looked more difficult! When we reached the mechanic's thoughts on head gasket failures and aluminium corrosion, I could sympathise with him!

Yes, there were twin overhead camshafts, but the engine comes apart with a central joint, just like the Javelin's. However, to get the pistons out from this 'over square' engine you have to take the gudgeon pins out first! To give access to the pin circlips, there are access ports in the sides of the block where you have to unscrew the blanking plugs first! Then you have to drive the pins out through these access ports. Sounds pretty complicated?

During the stripping process, the mechanic gives a lot of pros and cons that apply to any boxer engine. I found his explanation as to why these engines suffer from inherent high oil consumption interesting and perhaps explain why Jowett's said that you couldn't really expect better than around 200 miles to a pint? There were also some useful words on the function of the baffles in the sump, which we also have on the Javelin/Jupiter engines.

Anyway, I found the film interesting and a way of being involved with engine mechanics during our lock-down times!

Take care and have a Happy Christmas,

All the best,

David

[PAUL BEAUMONT]

This guy seems to post lots of videos on the topic of "why ......engines fail" (insert almost any motor manufacturer). I also looked at the Subaru one but found that little related to my experience. In the past 25 years I have covered well over half a million miles in a Subaru. On very rare occasions have I ever had to top up the oil between services which are now 12K miles. My last 3 Subarus have been diesels, the early one was one of the ones that broke crankshafts at about 108K miles.(engine rebuilt at Subaru cost!) The current one and its predecessor were both fitted with DPFs. As the engine cleans these they tend to "make" oil!
I suspect the greatest improvement since the time of the Javelin has come in cylinder bore technology. All loose liners today are centrifugally cast which improves the quality of the material. They are then plateau honed, effectively doing away with the need to "run in". Both features should extend engine life and reduce oil consumption. All new cylinder liners supplied by JCS for Javelin/Jupiters are made this way.

[Forumadmin]

I had my GTB Subaru engine spectacularly blow on the M4 after a tapping noise had developed over a few weeks and I was on my way to have it looked at. The small end bearing had worn and allowed the piston to contact the heads in this highly tuned engine.
Looking at the design and the manufacture over the 50 years of development of the engine you can see where Jowetts might have gone. One has to realise that only a couple of years of developement was ever done on the Jowett engine, not the 50 that the Subaru enjoyed.
Also the materials available then were poor and the machines clapped out. It is remarkable that we can still enjoy them.

[ajackson]

The video being discussed is probably this one:

https://www.youtube.com/watch?v=bJSYDBjkJNQ

[Forumadmin]

Interesting he said that one main bearing was not lubricated!
Also look at the 5 main bearing crank and the number of bolts holding the crankcase halves together. No wonder the engine was bullet proof.

[PAUL BEAUMONT]

So Keith, are you saying that in the Jowett case we should eschew those funny 4 cylinder things and retreat to the twins? at least Jowett had a few years to get them right - until they mucked it up with the CC Bradford that is!

[Keith Clements]

Perhaps they should have done what they did on my DB7 and bolt two twins together or even six of them.