Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Workshop Note - GDI Oil Breather

Water injection in one form or another has been around since early pioneer motorists noticed their early Edwardian internal combustion engine powered vehicles performed better on cold misty mornings. By the 1920's engineers had also understood that pushing air into an internal combustion engine above atmospheric pressure using a compressor was a great way to increase performance, forced induction also started to make a lot of sense on aircraft as they began to climb higher and higher, as we all know air becomes thinner at high altitude.

However, when you compress air you also heat it, so water injection was again used to lower the temperature of the incoming compressed charge of fuel and air. By WW2 things were getting really serious, to gain the advantage pilots need to be faster and fly higher so most fighter aircraft sported forced induction, typically a centrifugal vaned supercharger was used as with the Merlin V12, or turbo charging as seen on the 12-cylinder Allison used in the Lockhead P-38 Lightning.

As boost pressures increased so did intake temperatures, and to the point where engine destroying knock (detonation) became a real problem and as a consiquence water/methanol injection became essential. By the early 60's Chrysler were experimenting with turbo charging their passenger cars, to solve the detonation problem they also used water/meth injection on their Oldsmobile Jetfire model that ran the Turbo Jetfire engine.

After this intercoolers became more common, but water injection has more recently returned on the BMW M4 GTS that utilises water/meth injection in conjunction with intercooling to keep the engine safe at the higher boost pressures BMW wanted to run. Water injection is as old as the hills, it's also proven in combat and on many road and race cars. Not only does it lower intake temperatures which is especially helpful where a compressor is used as you can increase your igniting advance without destroying the engine with knock, but when the water enters the hot combustion chamber it immediately vaporises to steam creating an increase in cylinder pressure and so an increase in performance too.

It also keeps piston crowns, valves and combustion chambers spotlessly clean

Hi Dave

I've seen your previous posting about how you changed the pipework, which I propose to do, where did you source the crankcase inline filter? Is there a part number?

You also commented on the smaller pipe into the manifold - It is located at the lower rear of the inlet manifold, and if you feel under the lower rear corner you should find it. It's a push fit into a plastic boss on the inlet manifold, and can be detached, and the hole plugged into the manifold.. The hole into the manifold is plugged (with what?), is the disconnected pipe just left as is (open to air)?

Hi Les

Filter is here: https://www.ebay.co.uk/itm/204507409339?hash=item2f9d976bbb:g:9hgAAOSwpAtjyAKE&amdata=enc%3AAQAIAAAA8E8imZI6FwpE2ce6WjucZaxqCIoLTUQDCep5qug7vgAHF3lG6WRwfLE42krdj%2FaBXqe7T6%2B2k3WNXTjBdmwERTfXnvr6RlsYznEXAcs5U1wqka%2BbLOC2bKWW3cX%2FPPtwTZNnlgU7mC9HSKMzGGUOR0%2B3LTYjH2PzvtYO89UcmaSE15RuPI6PEuVtiDm6IIPN0iDmn4Zcfm0XpJNssAwosNQQqUbuHz8wYfP2V2CRBeVZ9rlQ9xhIaWe48qEjLyIu%2BNrR1EVOlwW0BV5vGQEIxjaYmffFw0MlIAcrYuf1hee%2FQsJo1vUT%2FVQD4J8l76EObw%3D%3D%7Ctkp%3ABk9SR7LUxdr5Yg

So I set that fliter up to look like it's in line, but blocked the end leading to the throttle body with a plastic cap. Don't cut the original pipe, then you can easily go back to original, just get a small extra piece.

The crankcase breather pipe is hanging loose. It's out of sight and isn't dripping any oil. To block the inlet manifold I used a length of hose, roughly tapered, with a bolt and washer stuck inside using silicon sealer. This is a push fit, and being tapered, can't work its way in. The washer is just to make sure.

More succinctly (and clickable) here: www.ebay.co.uk/itm/204507409339

Thanks Ian!

Further to the alarming state of the GDI inlet valves shown earlier in this thread, the state of play with my own GDI had to be investigated. Now on 20k miles with 10k under my ownership. A recent rolling road test showed the engine to deliver roughly standard bhp with the graph showing evenly progressiive torque and bhp delivery. There has never been any trace of a hair trigger throttle.

The offside crankcase breather was diverted away from the inlet some time ago and the nearside crankcase breather was diverted more recently.

The video early in this thread proved invaluable. However, removing the inlet manifold proved challenging. There are 6 bolts fixing the manifold to the block, 5 at the top and 1 bolt in an extremely difficult location at the bottom. A 3/8"square drive rachet, extension and socket is essential, as is a magnet on a stick to withdraw and reloate the bolts.

url=https://tm-img.com/image/SfWkv][/url]
The stainless steel angled bracket to the water pipe interferred with withdrawal of the manifold, which in the fore-aft direction was effectively locked in. Not wanting to disturb the coollant pipes and hoses, the manifold was eventually withdrawn by levering the pipes clear. The offending bracket was duly cut off and replaced with an aluminium detachable bracket. There are 2 separate plastic christmas tree type fixings that tie a wiring loom to the manifold beneath the intakes and 1 on the outside. These were detached prior to manifold removal. It was not necessary to detach any electrical connections other than the one to the throttle body.


The blue plastic angle bend holds the crankcase breather. The original short pipe was replaced with a single longer pipe which now feeds to a catch tank.



The short breather pipe originally fed into the 15mm ID hole at the base of the manifold. This has now been plugged up. In the foreground is the single fixing bolt location at the base of the manifold casting.


Valves as found. On inspection, all valves were in far better condition than expected. Seafoam was sprayed onto the valves and left for an hour or so before cleaning.


The inlet tract length is just over 100mm. A small softish brush with short rod was inserted in a longer tube for cleaning via the drill before removal with a rag poked down with a wooden stick. At the end of proceedings the brush detached itself from its rod and had to be rescued via a piece of bent wire.


The replacement aluminium bracket made replacement of the manifold a breeze.

Now both crankcase breather pipes have been diverted away from the inlet manifold, there should be no further carbon build up on the inlert valves.

However, from these findings it would appear the valves had very many more miles in them before becomming coked up. Under my ownership the valves were treated to the recommended Seaform squirt into the throttle body a few months ago. The car also gets treated to a trackday blow out every year. Other than that, the inlet valves have had a normal road going existance.

To conclude this operation, an interesting episode arose on trying to start up the engine.

Being very confident that everything had been put back exactly as found, no issue was expected. Jiggle the key around the immobiliser ring until the dash light extinguishes and off we go. The engine cranks at a good rate of knots for five or six seconds or so. Nothing doing – not even a burp or a fart. Give it a few moments to rest and try again. Same result. That sinking feeling starts to develop as two more attempts are unsuccessful.

All sorts of possibilities suddenly start to spin round. Did I inadvertently disconnect a wire? There is a spur wire from the harness that was not connected to anything. Has something untoward happened when I reconnected the battery? Has a relay failed? Has the fuel pump failed? Heaven forbid – have I damaged the valves?

Connect up the battery conditioner and sleep on it in order to hatch a plan.

This morning a plug is removed – totally dry. Connect it to its coil pack and connect up. Summon SWMBO to look for a spark while the engine is cranked. An intermittent spark confirmed. SWMBO then talks very persuasively to the engine to fire up as the spark plug is replaced. Next crank and there is just a whiff of a burp. Another better one on the following crank. The next crank and the engine gradually comes to life and with it a ten ton weight is lifted.

A full can of SeaFoam was squirted into the inlet as SWMBO held the engine at 2000rpm. Clouds of smoke gush from the exhaust, but once cleared the engine does feel very crisp at high revs. Roads are too damp and muddy for a full road test – that will follow later.

Moral of this story? Get SWMBO to have a stern word with the engine if it ever plays up!

We done Carol

That's why my current Roadster is nicknamed Basil !

Belle is now traumatised