Bleeh

Hey guys.

I ran my first compression test on my 1994 1.8. The results are as follows. 200/145/165/195. I placed a teaspoon of engine oil in valves 2/3 and the results changed to 150/170 (ish).

I ran the test while the engine was hot. I retested everything and came up with same results so I'm confident in my tester.

Before I start looking into an engine rebuild can anyone tell me of anything else I should try? Is it possible a weak gasket could lead to pressure loss between the two valves rather than it being more serious?

I'll be honest, I'm going about this a bit experienced, so please bear with me.

Cheers

Lee04vr

iTrader: (1)

More than likely the rings are worn, and it's time for a rebuild. I'm guessing you put some oil down the spark plug holes in cly 2 & 3 and the compression numbers jumped up some that's a dead ringer for ring seal.

kenwo91

iTrader: (1)

Just curious, miles?

ryansmoneypit

iTrader: (6)

Numbers didn't jump enough for me to suspect rings. I would lean towards valve leakage. A leak down test should be able to confirm.

dr_boone

iTrader: (1)

I agree with Ryan /\ also how well does the car run, does it smoke, run hot, idle rough. It could possibly be a head gasket a leak down might confirm that also.

Savington

iTrader: (31)

5psi change from dry to wet doesn't indicate ring seal

Ding ding. A leakdown test will confirm, but you have leaky valves on cyl2/3. You can pull the head and have it redone but it's not unheard of for a fresh head rebuild to overwhelm marginal oil control rings and cause immediate heavy oil consumption on an old bottom end. If you're on a budget, you may want to consider just swapping the entire motor with something a bit fresher and selling yours as a rebuildable core. Alternatively, rebuild yours and set yourself up for the future (forged rods at minimum).

patsmx5

iTrader: (16)

The fact that 1 & 4 have pretty good compression tells me the rings are probably ok, and you got some kind of leakage on cylinders 2 and 3, either valves (likely) or head gasket (not likely). Either requires pulling the head to fix. If the motor has 150k+ miles and whatnot I'd probably do a rebuild with forged rods. If it's low mileage or you're feeling cheap, just rebuild the head and reinstall.

Bleeh

To those who asked, the car has done 165k+ miles. It used to sit idle for several years before I got it.

The idle isn't purring but it isn't rough either - the engine runs fine otherwise.

I'll run a leakdown test over the coming days, which as a bonus gives me a good excuse to buy an air compressor., I'm looking at rebuilding the engine in the late summer due to be absent from home due to work in the foreseeable. It'll be my first engine rebuild but I'm excited by the idea.

Are forged rods really worth the money?

patsmx5

iTrader: (16)

If the bottom end comes apart, yes put some cheap forged rods in it. Search and read these forums about "rods only" builds. It's the most budget way to build the motor.

MstrBlk

Hey I have a similar problem, got 165/160/150/150.

I think there is a HG leak between 3 and 4. The valves are all probably leaking, and so are the rings.

How is this for a rebuild kit? This and some cheap forged rods?

dleavitt

iTrader: (1)

Listen to Savington. He is building me a forged bottom end because my tired one started crapping out oil after getting a fresh head.

Lee04vr

iTrader: (1)

I misread the original post I thought he said a cylinder went from 140ish to 170ish.

mmmjesse

If it runs fine, dont worry about it. Move on with life.