XK8 / XKR ( X100 ) 1996 - 2006

Compression Test Failure

Thread Tools
 
Search this Thread
 
  #41  
Old 08-12-2021, 04:19 PM
Phil m's Avatar
Senior Member
Thread Starter
Join Date: Jul 2021
Posts: 131
Received 15 Likes on 11 Posts
Default

Originally Posted by CA Jag
If you do the replacement engine approach, how do you figure out if it's any good? Private sale (if it runs), do a compression test. Commercial (like Jagbits) based on the warranty? Seems like doing the rebuild is a much better approach since you know what you're getting (and how many miles are on the motor).
Thanks for your advice all.

Thats another reason why I dont want to change the engine, am I replacing a dodgy one with another.

from reading your replies I'm going to hold off looking to replace the engine and look to open the Cam covers and try to get a look at the valves.

I'm really short on time but will try and find some asap, I know no specialist tools are needed for the above but am I going to need some go to ones?
 

Last edited by Phil m; 08-12-2021 at 05:48 PM.
The following 2 users liked this post by Phil m:
DavidYau (08-12-2021), michaelh (08-13-2021)
  #42  
Old 08-13-2021, 03:30 AM
dibbit's Avatar
Veteran Member
Join Date: Oct 2010
Location: Spain
Posts: 1,294
Received 510 Likes on 365 Posts
Default

Originally Posted by Phil m
I'm really short on time but will try and find some asap, I know no specialist tools are needed for the above but am I going to need some go to ones?
Above all you need a decent socket set with extensions and swivels to get to some of the harder to reach bolts on the cam cover. If you don't have what you need Amazon or Halfords have them for very little money.
 
The following users liked this post:
Phil m (08-13-2021)
  #43  
Old 08-13-2021, 08:53 AM
michaelh's Avatar
Veteran Member
Join Date: Apr 2014
Location: Jersey, Channel Islands
Posts: 4,164
Received 2,395 Likes on 1,554 Posts
Default

^^This

If you can lay your hands on a 1/4" or even 3/8" drive kit it will help with those awkward-to-get-to bolts on the rear.

Take note of the upper rearmost bolt on each cover (the ones not captive in a spacer). They're made out of magic metal so as not to affect the cam position sensor and should go back in the same location.

Good luck!
 
The following 2 users liked this post by michaelh:
Phil m (08-13-2021), piper 888 (08-15-2021)
  #44  
Old 08-13-2021, 01:48 PM
kansanbrit's Avatar
Senior Member
Join Date: Dec 2013
Location: Kansas
Posts: 787
Received 206 Likes on 152 Posts
Default

Originally Posted by NBCat
Under no circumstances is the crankshaft to be rotated in an anti clock direction as damage to the main and rod bearings is the result.
Very wrong, which shows you have no real engine knowledge. The reason for turning the engine backwards is that the chain tensioners are not designed to work in reverse and the chain may jump teeth.
 

Last edited by kansanbrit; 08-13-2021 at 01:52 PM.
  #45  
Old 08-13-2021, 05:41 PM
stu46h's Avatar
Veteran Member
Join Date: May 2012
Location: New Jersey
Posts: 1,035
Received 692 Likes on 376 Posts
Default

If I had this problem, this would be my simple approach.
If you squirt a little oil in each cylinder and the compression increases significantly, the problem is cylinder wall to piston ring sealing. Engine rebuild.
With no resolution there I'd pull the cam covers and check the primary and secondary chains for security. Rotate the engine to align the flats on the cams to make sure they're in sync. If exhaust cams don't move, the secondary timing chains are your problem, probably tensioners. Hopefully the pistons are OK because a valve and piston did not meet in anger. Keep fingers crossed.
If neither cam moves, the primary timing chains are the culprits.
If that's all OK and the cam flats align and the compression does not increase from the added oil, the heads are coming off and once they're off you'll probably find the problem upon inspection of the heads.
Good luck and please keep us posted.


 

Last edited by stu46h; 08-13-2021 at 05:43 PM.
The following users liked this post:
dfbender (08-15-2021)
  #46  
Old 08-14-2021, 12:33 AM
Pistnbroke's Avatar
Veteran Member
Join Date: Mar 2021
Location: Northampton, UK
Posts: 1,860
Received 737 Likes on 503 Posts
Default

Stu ..if you look in the photo you can see where the valve has kissed the piston..game over
 
  #47  
Old 08-14-2021, 04:23 AM
BobRoy's Avatar
Veteran Member
Join Date: Jul 2015
Location: Sacramento, CA
Posts: 1,527
Received 775 Likes on 466 Posts
Default

Originally Posted by Pistnbroke
Stu ..if you look in the photo you can see where the valve has kissed the piston..game over

I circled the 2 spots in red where it looks to me like the valves have made contact with the piston. I would guess that the timing chain on that bank has jumped 2 teeth.
Solution would be valve job on both heads and new chains, guides, and tensioners. There is a chance that there might be
damage to the piston and rod when it hit the valves. Damage could be to the wrist pin or rod bearings. There maybe no damage but if there is you could throw a rod at a later date. It has happened to me once.
I would still take the cam covers off and and align the flats. If you align the flats on the left bank and the right bank is noticeably out of alignment it will confirm my diagnosis.
My opinion is a replacement engine. I would try to find the history of the engine if you can. I like to get an engine out of a car that has been in an accident. At least you know it was running before it got in the accident.
 
The following 2 users liked this post by BobRoy:
dfbender (08-15-2021), piper 888 (08-15-2021)
  #48  
Old 08-14-2021, 05:57 AM
Phil m's Avatar
Senior Member
Thread Starter
Join Date: Jul 2021
Posts: 131
Received 15 Likes on 11 Posts
Default

Thanks for the information guts its certainly food for thought.....I think.
 

Last edited by Phil m; 08-14-2021 at 06:03 AM.
  #49  
Old 08-14-2021, 08:30 AM
David Dougherty's Avatar
Senior Member
Join Date: Dec 2016
Location: Jacksonville FL
Posts: 243
Received 110 Likes on 76 Posts
Default Confusing isnt it?

Originally Posted by Phil m
Thanks for the information guts its certainly food for thought.....I think.
It sounds like you are getting a lot of possible choices. There are things that you could know for sure right now. One is do you have low and uneven compression on your engine. If you still are unsure of the test results I would try to clarifly that. It is the easiet and cheapest diagnositcs you can do.
The second think you know is that on one piston you have zero compression. The piston does appear to have valve impact. Anyway a visual inspection will at least let you know if the tensioner has failed so you have to remove the valve cover on that cylinder bank.
Also one other check you may want to do would be to pull the oil pan off and look for metal and plastic in the sump. If there is a lot of metal there then it may indicate the amount of damgage to the engine. Pulling off the oil pan off is not difficult. If the tensioner did fail and the engine had metal to metal contact the sump should have residue plastic and metal.
None of these inspections will cost much and will hopefully give a better idea of what is going on.
 
The following 4 users liked this post by David Dougherty:
dfbender (08-15-2021), JimmyL (08-15-2021), michaelh (08-14-2021), Phil m (08-14-2021)
  #50  
Old 08-15-2021, 11:32 AM
Phil m's Avatar
Senior Member
Thread Starter
Join Date: Jul 2021
Posts: 131
Received 15 Likes on 11 Posts
Default

Thanks again for all the great advice all, because of work commitments and that I might have to move the car to another storage place I'm going to take some time and work out what I want to do.

Option 1 - Reconditioned engine.

I could easily be back to where I am after spending 1000's'

Option 2 - Change the secondary tensioners along with open the head up to check the valves & pistons.

Option 3 - sell the car at auction.

I like option 2 but If either the tensioners, Pistons or valves have gone how likely is it that it has killed the engine too?

I found a really good step by step guide to changing the tensioners, it even includes tools and replacement parts you need to buy.

 
  #51  
Old 08-16-2021, 10:26 AM
Kev-P-'s Avatar
Member
Join Date: May 2020
Location: Worsley, Manchester
Posts: 38
Received 21 Likes on 13 Posts
Default

I would just whip the covers off, 99% sure you will find out what your problems is and then the guys on the forum can give proper advice.
 
The following users liked this post:
Phil m (08-17-2021)
  #52  
Old 08-16-2021, 04:41 PM
STLTHMSTA's Avatar
Senior Member
Join Date: Jan 2020
Location: Maineville, Ohio
Posts: 420
Received 282 Likes on 164 Posts
Default

I don't have the answers for ya but don't give up! It may be worth saving and is oh so much a pleasure to drive. Good luck, TM
 
The following users liked this post:
Phil m (08-17-2021)
  #53  
Old 08-22-2021, 01:16 AM
Pistnbroke's Avatar
Veteran Member
Join Date: Mar 2021
Location: Northampton, UK
Posts: 1,860
Received 737 Likes on 503 Posts
Default

I know I said it before but when you did the compression test did you have all the plugs out and did you have the throttle fully open when cranking?
 
  #54  
Old 08-24-2021, 07:56 AM
JimmyL's Avatar
Veteran Member
Join Date: Oct 2008
Location: Virginia Beach, VA
Posts: 1,787
Received 417 Likes on 308 Posts
Talking Another unsolved mystery

I guess we'll never know. Or maybe ?
 
  #55  
Old 08-24-2021, 07:45 PM
stu46h's Avatar
Veteran Member
Join Date: May 2012
Location: New Jersey
Posts: 1,035
Received 692 Likes on 376 Posts
Default

Originally Posted by Pistnbroke
Stu ..if you look in the photo you can see where the valve has kissed the piston..game over
Yeah, that'll do it. Pistons and valves never should meet.
But for future reference...
 
  #56  
Old 08-25-2021, 05:05 AM
Phil m's Avatar
Senior Member
Thread Starter
Join Date: Jul 2021
Posts: 131
Received 15 Likes on 11 Posts
Default

Update - I've still not taken the covers off as yet due to work commitments and the fact I'm having to move the car at the end of the month but I will.

Further update to follow.

Cheers
 
The following 2 users liked this post by Phil m:
JimmyL (08-25-2021), michaelh (08-25-2021)
  #57  
Old 08-25-2021, 06:18 AM
JayJagJay's Avatar
Veteran Member
Join Date: Sep 2016
Location: New York New York
Posts: 4,236
Received 1,296 Likes on 897 Posts
Default

Originally Posted by Phil m
Update - I've still not taken the covers off as yet due to work commitments and the fact I'm having to move the car at the end of the month but I will.

Further update to follow.

Cheers
When you are able to get to it have a breaker bar and a good 6 sided socket (24mm I think?) handy so you can turn the motor to see valve operation and that the flats on each of the camshafts line up... is it 24mm?

Please ONLY turn the engine clockwise when looking from FRONT of the engine.
 
  #58  
Old 08-25-2021, 06:52 AM
Phil m's Avatar
Senior Member
Thread Starter
Join Date: Jul 2021
Posts: 131
Received 15 Likes on 11 Posts
Default

Thanks for the advice Jay.
 
  #59  
Old 08-25-2021, 08:58 AM
Kev-P-'s Avatar
Member
Join Date: May 2020
Location: Worsley, Manchester
Posts: 38
Received 21 Likes on 13 Posts
Default

Originally Posted by JayJagJay
When you are able to get to it have a breaker bar and a good 6 sided socket (24mm I think?) handy so you can turn the motor to see valve operation and that the flats on each of the camshafts line up... is it 24mm?

Please ONLY turn the engine clockwise when looking from FRONT of the engine.
Yep, 24mm.
 
  #60  
Old 08-25-2021, 10:36 AM
JayJagJay's Avatar
Veteran Member
Join Date: Sep 2016
Location: New York New York
Posts: 4,236
Received 1,296 Likes on 897 Posts
Default

Originally Posted by Kev-P-
Yep, 24mm.
Thank you, K! Need all the help I can get...
Just a warning,,, a long socket MIGHT not give you enough room with the fans in place... a short 24mm socket is your friend
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Erik
XJ XJ8 / XJR ( X308 )
14
07-19-2011 10:36 AM
willy-k
X-Type ( X400 )
5
02-18-2010 07:25 PM
Big Worm
S-Type / S type R Supercharged V8 ( X200 )
5
11-20-2009 11:12 AM
S-Type / S type R Supercharged V8 ( X200 )
7
02-25-2007 10:38 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


Quick Reply: Compression Test Failure



All times are GMT -5. The time now is 12:32 AM.