So, what did you do today?

[marshall_mosty]

Cool.. I'll have to try and catch. I watch that show on occasion.

When they interview JD, you can see my front passenger tire/fender. Michael's blown engine is also in the background.
When they interview Tommy, you can see down the passenger side of my car.
When they interview the auction guy, you see my Dad's 50 Oldsmobile

[blk96gt]

So I've been chasing a misfire for a while on cylinder #1. It's been throwing a P0301 (cylinder 1 misfire). I did check the compression at some point last year and it was fine. It really only seemed to happened at idle, so I hadn't bother checking the compression in a while, especially since the car made so much power on the dyno in January. Decided to check the compression tonight and sure enough, cylinder #1 was ~90, with the two others I checked at ~180. Oddly enough, this is the same cylinder that has had issues in the past. Changed injectors and coil packs when I got the new engine last year, so don't think either of those caused the issue.

Will probably go ahead and race the car this month and figure out what to do after that. Pretty sure it couldn't be anything else but piston/rings, but it still seems to run fine above idle and seems to have power. Had the car out this past weekend and ran great except cold idle...

[GlennCMC70]

Bent valve.
Pull the spark plug and stick an air hose in there that threads into the hole. Pressurize the cylinder and listen for where the air comes from - intake, exhaust, or crankcase. That will tell you where the issue is.

[Trublu]

Bent valve.
Pull the spark plug and stick an air hose in there that threads into the hole. Pressurize the cylinder and listen for where the air comes from - intake, exhaust, or crankcase. That will tell you where the issue is.

At TDC with both valves closed of course

[blk96gt]

Will give that a shot tonight or tomorrow. Will probably try the pouring a bit of oil down the cylinder trick and see if the compression changes first. I would think if the compression goes up it's likely rings.

[marshall_mosty]

Will give that a shot tonight or tomorrow. Will probably try the pouring a bit of oil down the cylinder trick and see if the compression changes first. I would think if the compression goes up it's likely rings.

Kevin,
I have a leakdown tester you can borrow if you cover the shipping costs to get it to you.

[blk96gt]

I may take you up on that offer. I'm going to try it with one of those air guns with a rubber tip on the plug hole tonight and see how that works. Will probably be more accurate to just use an actual tester though.

[BryanL]

Kevin,
I have a leakdown tester you can borrow if you cover the shipping costs to get it to you.

Can someone remind me when to do a compression vs leakdown test? If it passes a compression test is the motor okay?

Hey Marshall-if needed could get that leakdown tester from your tomorrow and use it this weekend couple of days if you don't ship it down to Kevin? I could ship it to him after the weekend. I'm doing a compression test anyway so this might be something worth doing??

[blk96gt]

A leakdown test can be used to determine where you losing the compression at. Valves, cylinder, etc. At least that's my understanding.

[marshall_mosty]

A leakdown test can be used to determine where you losing the compression at. Valves, cylinder, etc. At least that's my understanding.

http://www.motorcycleproject.com/mot..._leakdown.html