|
|
|
|
| Author |
|
|
Moderator
|
Compression Checks - Input?
Ok, today was the day I look closer into my engine running condition. My up the street neighbor was around last week and kindly gave his input on why my engine was running like doodoo. He used to work on Drag Racing engines back in the day. He could tell it was running on only 7 cylinders, first by visual at engine then at the tailpipe. I told him I would look further into that on a clear day (raining here lately).
Ok, pulled all plugs and checked their condition, they all (but 1) have a rich reading (black soot). My neighbor was right on! 1 plug looks like it's either not getting spark or fuel (I think fuel). I will check spark at end of wire to verify. Here is my compression readings: Cylinder 1 = 145 <--this is the clean plug with no soot. Cylinder 2 = 140 Cylinder 3 = 145 Cylinder 4 = 160 Cylinder 5 = 115 <--was 65 before I got the engine started last month Cylinder 6 = 155 Cylinder 7 = 155 Cylinder 8 = 155 Any input? 
__________________
1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD**
Last edited by MPDano; 12-26-2008 at 10:06 AM.. |
||
12-26-2008, 09:54 AM
|
|
|
Registered
Join Date: Dec 2007
Posts: 247
|
lack of spark, fuel could be washing the oil off the cyl wall to give you a low CR reading.
|
||
|
12-26-2008, 10:04 AM
|
|
|
Moderator
|
Sorry, updated original post to tell which plug was the clean one (no spark or fuel).
__________________
1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD**
|
||
|
12-26-2008, 10:06 AM
|
|
|
Moderator
|
Update:
Got spark at #1. Tried to check fuel flow from Distributor, but nothing really flows out (I removed the #1 Injector line "at dist" and the one next to it, for comparison). I cranked it but nothing really comes out of either one. So I take it that this is not a very good test. I am starting to think it's the injector. I don't have another one to test with, but was wondering (Russ) if I put just install one of the MB Injectors, or do I need to replace all 8?
__________________
1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD**
|
||
|
12-26-2008, 10:57 AM
|
|
|
Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
|
Swap two injectors, marvel mystery in the weak hole. Light a candle for Russ's motor and hope its not contagious.
|
||
|
12-26-2008, 12:41 PM
|
|
|
Moderator
|
Yup, it was the injector. I found a used one laying around and I sprayed it with carb cleaner and blew it out with a compressor. Installed it in #1 and it runs like a whole other car. The test will be after I get my wheels back and drive it.
__________________
1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD**
|
||
|
12-26-2008, 12:56 PM
|
|
|
|
Heavy Metal Relocator
|
Leo---
now that you have it running.....do another compression check. I am curious to see if the cylinder #5 is any better now that you've got a mile or two on it..... Hope it doesn't look like this:  --Russ
__________________
Absence of Evidence, is not Evidence of Absence. Bill Maher 8/4/09--- "I'll show you Obama's birth certificate, when you show me Sarah Palin's high school diploma." |
||
|
12-26-2008, 08:14 PM
|
|
|
Registered
Join Date: Nov 2006
Location: Sproat Lake, B.C.
Posts: 38
|
What do you think is the reason for the ring damage?
__________________
http://www.garage9.com |
||
|
12-28-2008, 09:51 PM
|
|
|
Registered
Join Date: Jan 2007
Posts: 11,758
|
A couple of teaspoons of the Mystery oil, and turn it over a little before you put the plug back in Even a couple of squirts of WD40 will do, but you don't want to get so much that the engine hydrolocks because there is a big plug of oil at top dead center.
Sticky rings like a little lube from the top. |
||
|
12-29-2008, 12:42 AM
|
|
