Notices
New Member Forum A place for new members to get their feet wet

Low compression - any hope?

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 02-17-2014, 03:47 PM
  #1  
New Member
Thread Starter
 
Benappleby's Avatar
 
Join Date: Feb 2014
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Unhappy Low compression - any hope?

Bought my rx8 a few months ago. All is fine apart from recently a few issues with hot start - takes a couple of goes - 20-30 seconds to get going. Was due a full service but decided to get a compression test done first - results not good. Cranking a bit slow which isn't the end of the world, but compression just below the minimum required. Average of about 5.5 on a crank of about 215. Conclusion - it's on its way out - am I right? General theme seems to be low compression means it's just a matter of time before the engine goes. How long do you reckon I've got? Dont do a lot of miles. Is it also wishful thinking to think that it's not all that bad and may just be a lot of carbon build up affecting the compression. A good carbon removal run using mazda a stuff or seafoam might help things a bit? Thanks.
Old 02-17-2014, 04:15 PM
  #2  
Registered
 
RotoryVirgin's Avatar
 
Join Date: Oct 2013
Posts: 155
Likes: 0
Received 0 Likes on 0 Posts
Nothing will fix it but a rebuild. There's no telling how much longer it will run, but hot start issues and mpg loss will get progressively worse. Flooding becomes much easier.

Carbon removal at this point could be a bad thing if the seals wore unevenly due to carbon build up.
Old 02-17-2014, 05:09 PM
  #3  
I HATE SPEEDBUMPS!
 
monchie's Avatar
 
Join Date: Nov 2007
Location: Las Vegas, NV
Posts: 8,549
Likes: 0
Received 7 Likes on 6 Posts
Your last resort could be seafoam. Does not mean its going to improved, but it could clean the carbon away. If not, then its time for a re-build or a re-man engine...good luck!
Old 02-17-2014, 05:17 PM
  #4  
Boosted Kiwi
iTrader: (2)
 
Brettus's Avatar
 
Join Date: Apr 2006
Location: Y-cat-o NZ
Posts: 20,523
Received 1,489 Likes on 839 Posts
do a decarb , slap a upgrade starter on , keep battery and ignition in good order and you will get many 1000s of trouble free miles yet .
Old 02-17-2014, 05:38 PM
  #5  
Day Walker
 
kevinande's Avatar
 
Join Date: Oct 2011
Posts: 585
Likes: 0
Received 18 Likes on 9 Posts
You can also add a little premix to the equation. It should help prolong its life a little, but in the end it will need to be rebuilt or replaced.
Old 02-17-2014, 06:02 PM
  #6  
Boosted Kiwi
iTrader: (2)
 
Brettus's Avatar
 
Join Date: Apr 2006
Location: Y-cat-o NZ
Posts: 20,523
Received 1,489 Likes on 839 Posts
Originally Posted by kevinande
but in the end it will need to be rebuilt or replaced
you could say that about anything ever built by man

The issue here is ... when is "the end" . I say it's a LOT longer than most allow it to be simply because they don't do the above ................
Old 02-17-2014, 10:37 PM
  #7  
Registered
 
Xeridae's Avatar
 
Join Date: Feb 2014
Posts: 53
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Benappleby
Bought my rx8 a few months ago. All is fine apart from recently a few issues with hot start - takes a couple of goes - 20-30 seconds to get going. Was due a full service but decided to get a compression test done first - results not good. Cranking a bit slow which isn't the end of the world, but compression just below the minimum required. Average of about 5.5 on a crank of about 215. Conclusion - it's on its way out - am I right? General theme seems to be low compression means it's just a matter of time before the engine goes. How long do you reckon I've got? Dont do a lot of miles. Is it also wishful thinking to think that it's not all that bad and may just be a lot of carbon build up affecting the compression. A good carbon removal run using mazda a stuff or seafoam might help things a bit? Thanks.
Out of curiosity how many miles does it have on it?
Old 02-18-2014, 01:33 AM
  #8  
New Member
Thread Starter
 
Benappleby's Avatar
 
Join Date: Feb 2014
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
58000 miles. Runs great. I can manage my journeys so I never do a hot start (and I can get it started if I have to). On reflection power seems a bit down pulling away which Is to be expected but I don't really notice. At the moment I've just got a piece of paper telling me the end is near and not sure what to do about it! Going to run some seafoam through and see what happens.
Old 02-18-2014, 10:37 AM
  #9  
Registered
 
Phoenix_'s Avatar
 
Join Date: Dec 2013
Location: Finland
Posts: 17
Likes: 0
Received 0 Likes on 0 Posts
Any misfires? I was running fine with hot start issues for some time, but the situation got worse, over a course of just a couple of days, to a point where the car would not run. Misfires under heavy load was the first real symptom besides the hot starts.
Old 02-18-2014, 12:59 PM
  #10  
Boosted Kiwi
iTrader: (2)
 
Brettus's Avatar
 
Join Date: Apr 2006
Location: Y-cat-o NZ
Posts: 20,523
Received 1,489 Likes on 839 Posts
Originally Posted by Phoenix_
Any misfires? I was running fine with hot start issues for some time, but the situation got worse, over a course of just a couple of days, to a point where the car would not run. Misfires under heavy load was the first real symptom besides the hot starts.
Again , an engine with low compression runs just fine (apart from a small loss in top end power )if everything else is good .
Low compression does not cause misfires.
Old 02-18-2014, 01:09 PM
  #11  
Rotary Evolution
 
Karack's Avatar
 
Join Date: Oct 2011
Location: Central FL
Posts: 853
Likes: 0
Received 2 Likes on 2 Posts
Originally Posted by Brettus
you could say that about anything ever built by man

The issue here is ... when is "the end" . I say it's a LOT longer than most allow it to be simply because they don't do the above ................
i agree, if you can squeeze another 10-20k miles out of an engine before replacing it and follow that recommendation then your engine replacements will span out further.

the focus should be on the cranking speed and your ignition system anyways, replacing the engine won't fix those growing problems.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Shnifty
Series I Tech Garage
23
12-18-2015 12:49 PM
Quiggs321
New Member Forum
2
09-03-2015 04:28 PM
dbarber
Series I Trouble Shooting
14
07-25-2015 01:34 PM
Bamaham
New Member Forum
2
07-23-2015 08:08 AM
thedragonrotar
New Member Forum
1
07-22-2015 08:46 PM



You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Low compression - any hope?



All times are GMT -5. The time now is 02:24 PM.