All Motor All Motor Advanced Performance. Talk about Engine Swaps, Internal Engine work. Not your basic Y pipe and Intake Information.

3.5 Compression Test Results = Issues

Old 07-30-2011, 07:08 PM
  #1  
Senior Member
Thread Starter
iTrader: (4)
 
TunerMaxima3000's Avatar
 
Join Date: Jul 2006
Location: Ontario, Canada
Posts: 5,548
3.5 Compression Test Results = Issues

As some of you know, I recently picked up another 5th gen. 5.5 to be exact.
The car ran like crap, to keep things short, so I started investgating farther today. I know the front bank spark plugs are bad, today I found the rear to be not too bad, but I'll be replcng all 6 of course.
I am admittedly a NEWB with this level of engine work, so please be patient with my questions. I do have a pretty good theoretical knowledge, but I haven't dug into engines practically yet, other than a 5 man 3406 (diesel) rebuild in school, different ball of wax though.

I've copied this over from the 5th gen forum, as I'm looking for experienced engine advice, I thought this would be a good place to drop it as well. Sorry for the double post.

Down to the main issue, Compression.

FYI, FSM reads the following:
Standard Compression = 185 PSI
Minimum Compresion = 142 PSI
Maximum Difference between cylinders = 14 PSI


My test results (PSI) :

Cyl #2 >>> DRY test (base) = 150 >>>>> Wet = 210***
Cyl #4 >>> DRY test (base) = 165 >>>>> Wet = 235***
Cyl #6 >>> DRY test (base) = 195 >>>>> Wet = 245
Cyl #1 >>> DRY test (base) = 200 >>>>> Wet = 230
Cyl #3 >>> DRY test (base) = 200 >>>>> Wet = 245
Cyl #5 >>> >>>>>>>>>> Wet = 235


Cylinder#5 has oil in the spark plug hole, so I was unable to get a baseline for that cylinder.

Obviously, it seems cylinder #2 and #4 have bad rings, I thought this was strange though, does anyone else feel that way? I find it hard to believe that just 2 cylinders would wear the rings out and the rest are perfectly fine. Especially 2 cylinders that are right next to each other.

When I did the dry tests I assumed I had a bad headgasket, (hoped it was a headgasket anyhow) but the wet tests don't really lie, so I guess I'm asking if you guys think there could be anything else that is wrong, or am I into doing piston rings on #2 and # 4?
I should mention, the spark plugs on #2 and #4 were carboned up BAD, which re-enforces bad rings IMO.

Oh and can we pull the piston from the bottom? Do we need to pull the whole crank to pull one or two pistons, or can I sneak them out of there?

Also, I am assuming that the oil in my # 6 spark plug hole is just from a bad seal on the valve cover? Can these be replaced without replacing the whole cover?

Thanks for any help here boys, I'd love to get this car up to snuff so I can decide what to do with it.


Oh, here's a couple pics of the process, just cause we all like pics so much







Ready for bed:
TunerMaxima3000 is offline  
Old 08-05-2011, 05:38 AM
  #2  
Senior Member
iTrader: (8)
 
Join Date: Dec 2003
Posts: 4,097
So far, all compression test I have seen from a 3.5L FWD have shown that the front bank has lower compression (all 3 cylinders). I came to this observation when I did a compression test on my built motor and turned out to be:

200 , 197 , 200
175 , 170 , 170

Bottom row being the front bank, this is on a 8.8:1 compression 3.5.
However, the engine is fine, no oil consumption and oil analysis have returned satisfactory. I blame the FWD intake manifold, there is uneven air distribution between both banks (I have proven this by logging AFR on each bank). Also if you have PCV hooked up, oil will go to the bottom portion of the manifold, which is why you see different color runners on the manifold.

The oil on the coil is most likely from bad seals on the valve cover, id change that soon. I wouldnt worry much about the compression to be honest.
streetzlegend is offline  
Old 08-05-2011, 10:46 AM
  #3  
^ Jeff™
iTrader: (11)
 
MrEous's Avatar
 
Join Date: Sep 2002
Location: Garland (DFW), TX
Posts: 3,775
2 & 4 are closest to the precat in the front, no?
Curious if the front precat may have had some blow-back into the exhaust valves compromising those rings.
Originally Posted by streetzlegend View Post
So far, all compression test I have seen from a 3.5L FWD have shown that the front bank has lower compression (all 3 cylinders).
'All' front cylinders being lower than rear is fine. 2 of his 3 front cylinders having lower compression than the 3rd cylinder is an issue.
The oil on the coil is most likely from bad seals on the valve cover, id change that soon. I wouldnt worry much about the compression to be honest.
Agreed...get with DAVEB and get some 6th gen valve covers to fix that issue.
MrEous is offline  
Old 08-05-2011, 08:32 PM
  #4  
Senior Member
iTrader: (8)
 
Join Date: Dec 2003
Posts: 4,097
Originally Posted by MrEous View Post
2 & 4 are closest to the precat in the front, no?
Curious if the front precat may have had some blow-back into the exhaust valves compromising those rings.
We can rule out that its not the precat. I dont have any cats at all and still got this reading, as well as others with same readings and no cats.
streetzlegend is offline  
Old 07-10-2017, 10:46 PM
  #5  
Newbie - Just Registered
 
Join Date: Jul 2017
Posts: 1
Ahh

Roarke333 no these cars need fusebox on term and you can get them from nissan relatively cheap
Rene Perales is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
pktaske
6th Generation Classifieds (2004-2008)
1
05-06-2016 07:49 AM
MaxLife17
New Member Introductions
5
09-08-2015 02:36 PM
Maxima30
5th Generation Maxima (2000-2003)
2
09-07-2015 06:13 PM
Maxboy23
5th Generation Maxima (2000-2003)
6
09-04-2015 06:04 PM
pktaske
6th Generation Maxima (2004-2008)
0
09-04-2015 08:40 AM


Thread Tools
Search this Thread
Quick Reply: 3.5 Compression Test Results = Issues


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.