1.6L 8v burning oil on downhills only

[drew88]

Hi,
I have a 1988.5 suzuki samurai with a 1990 8valve 1.6L motor in it. I bought the car this way, so I don't know exactly what car the donor motor came out of, but I am told it was a 1990, and I'm assuming it was a sidekick. It is not using the stock FI, it is using my samurai's stock carburetor.
Everything works great, but I have noticed that during, and shortly after driving any downhill trails I burn oil. Since this only seems to occur when I take it downhill, I'm hoping it's a problem with a missing/clogged breather or something, rather than something like worn valves that would burn oil all the time.

If anyone has any ideas on likely culprits or troubleshooting methods to narrow down the range of possible causes, I would love to hear them.

Thanks,
-drew

[fordem]

I can think of two possible causes - either the PCV or the valve seals - if you're going downhill with the throttle closed, the vacuum builds up and sucks the oil through.

[jtgh]

ditto , breather , pcv clogged, check end to end for free flow of fues
from VC to induction via the PCV valve.
or intake seals bad. high vacuum sucks oil thru valve stems.
or the stems or badly worn.

how you know oil , is burning, looking backwards down hill or what?

[drew88]

yeah, lots of smoke behind me and noticeable oil level decrease after driving some downhill trails. i checked the PCV and it seems ok, meaning i can hear it rattle and it one allows air flow in one direction. i think it's looking like intake valve seals...

[jtgh]

down ,hill means ?

coasting down hill foot off gas pedel , in gear, using engine compression to brake car.?
doing that?
this creates a super vacuum below the intake valves. 29 inches or near.
and sucks oil thru the valve seals. (then gets burnt)

this is the worse case test for these seals.

2 fixes.
1: pull head fix em. (replace seals)
or
2: apply shop air to each cyl. in turn with spark plug adaptor.
and compess valve spring and pop keepers. next , 2 new seals.
repeat (good weekend DYI project, $10 for seals $10 for valve cover gasket.

some just put in small rope into spark hold like 18 inches, then raise pistion compressiong rope and freezing valves in position.
and repeat for each hole.

a complete compression test and cyl lead down test will show any weakness in valves and pistons rings too.


I forgot to say,
they make a valve spring compressor that only touches the spring.
not the under head kind.

[drew88]

thanks for the help! any idea on part numbers or a place i might find the valve spring compressor and spark plug air line adapter you mentioned?

and to answer the question, yes, it's downhill in gear no throttle, engine braking that causes the oil burning problems. i don't really notice any burning other than when i'm engine braking. it's bad enough that no one wants to be behind me on downhill trails

[jtgh]

if it coming out tail pipe
and'
PVC is good , rattles and acks as good check valve.
its the seals.

some love to smoke but not out tail pipe, but oil drip of bad orings of distributor mount to collecter end.

any auto store has em,, harbor Freight has spring tool.
some ppl take old spark plug , smash away(goggles) the insulator and weld on an air line fitting to the spark plug shell. DYI.

16v would be back breaker, but your 8v not too bad.

yours are probably cracked.

some ppl try this additive to the oil that softens seals but is risky or not effective.
it is effective in some cases.