Jump to content
SAU Community

R33 GTS25T Compression Issue

JasonMate
 Share

Recommended Posts

JasonMate Apprentice

JasonMate

Posted
Posted

So i brought this car a year ago with 250k on it with a blown ECU and a tight cam belt, Fixed that and is was a new car again. The problem has been that the compression cold is 140psi throughout the 6 and once hot they all drop evenly 20psi down to 120psi throughout the 6. its been like that for a year now and hasn't changed. it doesn't use oil really and doesn't fill up the catch can. the k&n filter on the catch can looks abit oily however. There's no noticeable blow by just a puff of white smoke out the catch can when you give it a hard rev.

I haven't done a leakdown test yet I've been putting it off. my question is what causes compression to drop like that? i have no information on the history besides it was owned my crackheads and it sat dormant for possibly more then 5 years. the motor looks super clean for how many km's it has and how trashed the suspension is. the car runs perfect but i can feel the 20psi loss as the car warms up.
i was thinking someone put a thicker head gasket on to drop the cr but that still doesn't answer the compression drop. its suppose to rise isn't it lol.
I've asked many mechanics and they cant explain it.
Hope someone can help!
Thanks.

Link to comment
https://www.sau.com.au/forums/topic/482142-r33-gts25t-compression-issue/
Share on other sites
Rusty Nuts Experienced

Rusty Nuts

Posted
Posted (edited)
3 hours ago, blind_elk said:

Have you done a wet compression test?

Its a good idea, but it will confirm worn rings. The suspension didn't get rooted because the crackies drove it to church on Sundays. Or down to Supercheap for new filters, before the car wash.

Edited by Rusty Nuts
additional information
  • Like 1
JasonMate Apprentice

JasonMate

Posted
  • Author
Posted (edited)

hmm, its running 10psi atm, iv blown 2 turbos so far going any higher on the stock ones. Im still confused why the compression dropped 20psi just from warming up, and even more so why its 120psi hot and cold a year later. wouldnt it drop down to say 100psi once warmed up if its worn that much in the time iv owned it. if compression should be around 160-170+ and i have 120, shouldnt there be quite abit of blowby?
I forgot to take the crank case vent valve out of the manifold to get a true reading of how much blowby there is, i dc that. i took the catch can hose out and you can bearly notice air coming out, you have to squeeze the hose end and then its enough to feel like a gentle flow of air. 0 smoke. same if you give it a rev.
iv used the same comp tester for years to eliminate getting different readings.

Edited by JasonMate

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • sinn3r
      R34 Skyline climate control unit transistor

      By sinn3r · Posted

      Hi all,   long time listener, first time caller   i was wondering if anyone can help me identify a transistor on the climate control unit board that decided to fry itself   I've circled it in the attached photo   any help would be appreciated
    • Kinkstaah
      Blue slip

      By Kinkstaah · Posted

      I mean, I got two VASS engineers to refuse to cert my own coilovers stating those very laws. Appendix B makes it pretty clear what it considers 'Variable Suspension' to be. In my lived experience they can't certify something that isn't actually in the list as something that requires certification. In the VASS engineering checklist they have to complete (LS3/NCOP11) and sign on there is nothing there. All the references inside NCOP11 state that if it's variable by the driver that height needs to maintain 100mm while the car is in motion. It states the car is lowered lowering blocks and other types of things are acceptable. Dialling out a shock is about as 'user adjustable' as changing any other suspension component lol. I wanted to have it signed off to dissuade HWP and RWC testers to state the suspension is legal to avoid having this discussion with them. The real problem is that Police and RWC/Pink/Blue slip people will say it needs engineering, and the engineers will state it doesn't need engineering. It is hugely irritating when aforementioned people get all "i know the rules mate feck off" when they don't, and the actual engineers are pleasant as all hell and do know the rules. Cars failing RWC for things that aren't listed in the RWC requirements is another thing here entirely!
    • GTSBoy
      Best place to order Authetic R32 Parts in Japan

      By GTSBoy · Posted

      I don't. I mean, mine's not a GTR, but it is a 32 with a lot of GTR stuff on it. But regardless, I typically buy from local suppliers. Getting stuff from Japan is seldom worth the pain. Buying from RHDJapan usually ends up in the final total of your basket being about double what you thought it would be, after all the bullshit fees and such are added on.
    • GTSBoy
      Ethanol Content Sensor - Always at 11%?

      By GTSBoy · Posted

      The hydrocarbon component of E10 can be shittier, and is in fact, shittier, than that used in normal 91RON fuel. That's because the octane boost provided by the ethanol allows them to use stuff that doesn't make the grade without the help. The 1c/L saving typically available on E10 is going to be massively overridden by the increased consumption caused by the ethanol and the crappier HC (ie the HCs will be less dense, meaning that there will definitely be less energy per unit volume than for more dense HCs). That is one of the reasons why P98 will return better fuel consumption than 91 does, even with the ignition timing completely fixed. There is more energy per unit volume because the HCs used in 98 are higher density than in the lawnmower fuel.
    • GTSBoy
      Blue slip

      By GTSBoy · Posted

      No, I'd suggest that that is the checklist for pneumatic/hydraulic adjustable systems. I would say, based on my years of reading and complying with Australian Standards and similar regulations, that the narrow interpretation of Clause 3.2 b would be the preferred/expected/intended one, by the author, and those using the standard. Wishful thinking need not apply.
×
×
  • Create New...