No compression #5
Thread Starter
|
8th Gear
Joined: Aug 2021
Posts: 8
Likes: 0
No compression #5
I have a 1999 f-550 has 225,000 miles and it had been running rough I decided to just start at the bottom and work my way up as to why, so I checked compression. so far I have only checked the passenger side and all have around 330-340 except 5 which only registered 100 checked four times made sure my tool was tight same results. My question is where do I go from here? What could be causing this? I bought the truck to fix and sell hoping for a profit but this may be a flop. Any help is appreciated and thanks in advance.
Butt-Head
Joined: Apr 2004
Posts: 9,453
Likes: 2,936
From: Reed Point, MT
When it's running, do you have a lot of crankcase pressure escaping from the oil fill cap in time with the miss?
If so, it's replacement engine or rebuild time.
If the crankcase pressure isn't happening, then it's time to do a leakage test with pressurized air. It could be a bad seat or valve or even a bent pushrod or broken rocker arm.
If so, it's replacement engine or rebuild time.
If the crankcase pressure isn't happening, then it's time to do a leakage test with pressurized air. It could be a bad seat or valve or even a bent pushrod or broken rocker arm.
Thread Starter
|
8th Gear
Joined: Aug 2021
Posts: 8
Likes: 0
Could I get some instructions on how to perform the air test I’m assuming it’s just a leak down test. I haven’t checked for blowby at the cap and I’ve already got the valve cover off but a leak down test would reveal ring issues as well. Could an injector or cup cause low compression or just ring and valve issues.
Thread
Thread Starter
Forum
Replies
Last Post
benbuilder
Performance & General Engine Building
6
Aug 17, 2019 07:08 PM
gysgtbigdaddy
Y-Block V8 (239, 272, 292, 312, 317, 341, 368)
1
May 28, 2013 02:03 PM
