4AGE smallport low compression help!

[shortround]

Hey guys,

I recently installed a smallport 4AGE to use temporarily whist waiting for an engine rebuild.

It was sold as a "running engine", with the ad saying 150psi across all cylinders - sounded a little low, but I was only planning on using it till the end of the year.

However after I installed the motor, I found that this was not the case. It feels and sounds like its running on 3 cylinders, and is blowing white smoke.

Here are the results of the dry compression test after warming the engine to operating temp:

1 - 190
2 - 60 and did not hold pressure
3 - 60 and did not hold pressure
4 - 210

It's weird that the gauge looses pressure on cyls 2 and 3 after maxing out at 60psi when cranking. I don't think it's something I am doing wrong, as I immediately swapped the gauge back to cyls 1 and 4, which held pressure until I pressed the release valve, as did the results on cyls 2 and 3 below VVVV

I then did a wet compression test on cyls 2 and 3, with about 1/2 tablespoon of oil:

2 - 205
3 - 220

There is also a reasonable amount of pressure coming out of the dipstick hole, but there is NO oil in my catch can, so it sounds like its probably rings?

It was suggested that I do a leakdown test, however I don't have an air compressor etc.

Where would the issue likely be?? Bottom end or head gasket/top end? The later I can fix with spares I have lying around.

Cheers,
Andrew.

[ach_66]

White smoke and low compression between 2 and 3 sounds like head gasket to me?

Burning oil would be blue smoke and smelly.

[lolwat]

if you oil them, noramlly help the rings seal, put a vacume guage on it see how still the needle is (can show sign of valve issues) my 4a has a ring (pos piston) it fills a medium milo can with oil in like 5 mins, and covers engine bay in oil(rear muffler is dripping with oil)

[maxhag]

As "Azz" has said above, sounds like a HG blow between two cyls. Has actually happened to me before, with simular symptoms....

Ie; This -
http://www.ae86drivingclub.com.au/dcimages/1/1/1/401178.jpg

[timbo]

Those compression numbers on 1 and 4 are relatively low. When I did a compression test on my smallport it was 225 on all four. As everyone said it seems to be a blown HG, take the head off and have a look, worse case is you need to pull the motor out anyway.

[Matt]

I'd put money on the head gasket being gone as well

[shortround]

Thanks for the replies lads. I'm hoping it's the head gasket or even the head as I have spares of both lying around. I'll start pulling the head off tonight.

timbo - my compression gauge is just an el-cheapo of ebay, so I am not too worried about the exact numbers. The engine I recently pulled out of the car had around 200-215 across all cyls and it still pulled strong!

[timbo]

Ah righto, they are never foolproof but give you an idea. Good luck with it, HG is easy, rings will be easy because you've already taken the head off!

[lolwat]

if you think its between cyclinders, put a plug in 2 and test 3 see if ti changes at all

[shortround]

if you think its between cyclinders, put a plug in 2 and test 3 see if ti changes at all

Thanks Michael, I'll give it a go.

Need to recharge the battery first :)

[lolwat]

either way the heads gotta come off

[shortround]

Just ripped the head off... I can't see anything obviously wrong, so rings are looking more likely?

Head gasket had no issues, seems to be a metal one? and looks pretty new:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401550.jpg

Head looks fine. Will test if the valves are sealing tomorrow:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401552.jpg

Nothing visibly wrong with the block. The pistons also look pretty clean around the edges. There does seem to be more build up around the top of cyls 2 and 3 though:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401554.jpg

I get the feeling the block was rebuilt recently. All gaskets and seals look new-ish, along with the welsh plugs and the pistons are pretty clean... maybe the rings in cyls 2 and 3 didnt bed in after a rebuild??

Could it be anything else but rings?

[SamsTA22]

There are so many places air can leak from.
Assuming the headgasket wasn't blown, and there's no leakage from the valves, Piston rings are a good bet. The rings would also explain your initial symptoms.

[lolwat]

considering when you get a wet comp test it went straight up, i would go with rings, as said before

if it was rebiuld recently your coolant galleries look pretty poo already

number 1 looks like its been burning oil also, may be wrong, but if i pulled a plug out and it looked like that chamber i would say its burning oil

[timbo]

Is it just me or is cylinder's 1 and 2 look over oily?

[lolwat]

Is it just me or is cylinder's 1 and 2 look over oily?

exactly what i was thinking

[tottacrolla]

"Head gasket had no issues, seems to be a metal one? and looks pretty new:"

If it is a metal after market gasket, TRD etc. they can be difficult to get to seal properly and typically
requiring a head and block skim.

[lolwat]

its not metal, well not like ones ive seen, look how its separated on the block

[shortround]

Thanks for the input guys!

I think the angle of cyls 1 and 2 are making them look oily? Here is another photo:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401606.jpg

I don't know much about head gaskets, but I just took another look and most of it is metal? took some more pics:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401608.jpg
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401610.jpg
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401612.jpg

And from underneath:
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401614.jpg
http://www.ae86drivingclub.com.au/dcimages/4/1/1/401616.jpg

Also I poured some oil in each of the bores to see if it leaks past the rings, but more than 24 hours later its all still there.

[skin]

wet comp test over 200 each cyl theres hardly an issue there lol

[shortround]

Yesterday I stripped the head down for cleaning and came across something which might explain the low comp in cyls 2 and 3...

http://www.ae86drivingclub.com.au/dcimages/4/1/1/404513.jpg

http://www.ae86drivingclub.com.au/dcimages/4/1/1/404515.jpg

Thinking again that it might not have be the rings, I have since put the head back together after cleaning everything and bolted it back onto the block with a new cheapo head gasket I had lying around. Will have it running again in the next couple of days.

[timbo]

Slackness or laziness is to blame. You should of had your head faced and taken better care.

[shortround]

Yeah maybe. I just cleaned it and slapped it back together as its something to run while waiting for my 4agze build.

Bought it for cheap off some guy who had never used it since he bought it. Was told it was a runner - but it wasn't!

[shortround]

Other dodgy things I came across was a backwards camshaft journal and silicone/gasket goo all around the dizzy hole.

[timbo]

Oh dear! Sounds like a real mess, people can certainly fuck shit up.