Challenging issue for Gurus with Suzuki knowledge..

[Stifull]

We recently bought another Suzuki Swift GTi 1991 model . We got it very cheaply and the owner who had bought it only a few months ago said it had an oil leak. When we investigated we found the oil was dripping out of the air filter.. We replaced the soggy filter with a pod and blocked off the PCV inlet and have the PCV hose running into a home made catch can. It can fill a 1 liter bottle with oil from the PCV in less than 150 klm...LOL... Now normally "blowby" that causes excessive oil/vapors/smoke etc coming out of the PCV but this car has 200lb compression in all 4 cylinders and runs very well and blows hardly any smoke..All the drain holes around the twin overhead cams are clear. The head gasket must be on the right way or it wouldn't be getting oil up there at all. The engine has been rebuilt and is very quiet with no knocks or rattles and sounds very happy. It was going to be used as a track car and has had work done on suspension and brakes and had a brand new Sparco racing harness still in the box in the back. The only other mod visible is the original intake plenum has been replaced with a larger Nissan Silvia we think type which allows for better/more air as well as bigger injectors and fuel rail. The Gtis don't only have a PCV coming from rocker cover, they also have a one way valve/pipe that goes across to the plenum which sucks out of the rocker cover. We have checked the one way valve is working and facing the right way.
So... We have swapped the rocker cover with a different one and checked that the baffle plate at the inside top of the cover wasn't blocked or on the wrong way. Can't for the life of me figure out how it can blow a liter of oil out the top of the rocker cover in a 100klm drive.. If you drive it like an old lady it will only pump 25ml in 100klm.. It seems the accelerator pedal has turned into a 2nd oil pump but not in a good way. The guys in the GTi club can't figure it out either. The 200 psi of compression, smooth quiet powerful engine doing this has them stumped.. Someone said valve guides may be very worn but I would think it would be blowing a LOT of smoke..So what can put that much pressure in a rocker cover ?????? If you take the oil filler cap off ,even at idle there is a lot of air coming out. What else can pressurise the top end soo much..

[Yowie]

Interesting problem.

To ask a silly question, how reliable is a compression test in terms of predicting blowby? If you had a load of blowby the symptoms would make a lot of sense.

We replaced the soggy filter with a pod and blocked off the PCV inlet and have the PCV hose running into a home made catch can.

Is "clean" air being drawn off the catch can and into a source of vacuum? (or is the catch can just venting to atmosphere now?). If the latter the lack of a vacuum pull on the crank case could be raising the typical crank case pressure.

Can you upload any photos/diagrams of the current routing of all crank gas out of the engine and into whatever termination point/s?

[bigBADbenny]

Find a spare oil cap and measure pressure using a boost/vacuum gauge, over 3000rpm.

If the cap is on the rocker cover, repeat the test with the gauge on the crankcase vent or eg dipstick.

If you’re going positive with throttle over 3k rpm: compression issues.

Repeat the test with the gauge on the inlet manifold post throttlebody.

It should be negative on idle and cruise, and atmospheric on wot.

If the gauge bounces with rpm on idle, that’s burnt valve etc.

Are the valve clearances in spec, eg cold/warm spec?

Is the timing correct, eg inlet vacuum should drop on the vacuum gauge as eg the dizzy is rotated to the correct spot with the engine at eg 2k rpm.

Between those tests you may have your answer.

90BADC05-3606-4A23-BC1E-4F45FD432339.jpeg (165.43 KiB) Viewed 2165 times

Here’s the classic engine diagnosis via inlet manifold vacuum diagram ^.

Otherwise check you’re using the stock recommended amount of oil in the sump.

You could have a short dipstick meaning you’re running way too much oil in the sump.

Grouse car, jelly much

Research begins
https://www.redlinegti.com/forum/viewto ... 50#p301712

https://www.redlinegti.com/forum/viewto ... =7&t=30791

Stock pcv is tiny:
https://www.redlinegti.com/forum/viewto ... 11&t=27819

[Stifull]

Thanks for the detailed reply. I think the first step is to replace the one way valve to the plenum. It is on the right way but feels like it is spring loaded so may not be opening easily enough although with the amount of pressure in the cam cover and the suction from plenum I would think that should open even the most tight one way valve..Maybe not. We will swap it and see. In the meantime I have forwarded you reply to a friend who gave us the black GTi (now written off) and has 5 of his own that he races and is very familiar with them and does all his own engine rebuilds etc. His are all set up for different types of racing..eg..track and legal street .. His turbo street racer is quicker around Lakeside than my rex, which is very quick..