Jump to content
View in the app

A better way to browse. Learn more.

300ZX Owners Club

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Evening all

 

That time on a Sunday where I like causing misery towards myself..

 

I have just done a compression test on my car, and the results were, erm, well depressing i'd say. 100 psi average..

 

So the question is since you are the guys in the know, where is the best / fairest place to get engine parts for it?

 

Thinking of forging whilst i'm in there, but would like to price up costs ect.

 

Thank you in advance

Featured Replies

When you say average, what were the actual numbers? Why did you perform the test? Is the car showing symptoms of poor health? Is your testing equipment calibrated or verified?

  • Author

105psi, 95 psi, 100 psi ect

 

It cranks over very quickly and didn't sound over healthy when I started it earlier, so thought i'd check it.

 

Must admit the equipment isn't calibrated. Can't see it being 50psi out though

Agreed. Just seems a touch odd that it's uniformly low. Is it exceptionally high mileage? Does it burn oil? Generally I've seen these engines fail on a cylinder or two rather than evenly though out. I've got a 60k block sat I'm my workshop at present that still has very clean clear hone marks on the bores and the ring gap was well within factory spec. What I'm getting at is that for an average mileage engine I'd be surprised if the rings are worn out evenly through use as apposed to mechanical failure. I suppose it might have suffered from oil starvation but then I'd expect bottom end damage too.

  • Author

I see what you mean. I think the previous owner may have abused it, it has a boost controller in it that goes up to 1.4 bar, stock turbos, stock guts in the engine ect.

It uses a small amount of oil yes, but you don't see any cloud of smoke bellowing out of the exhaust. The mileage is 109,000. A little high yes, but I didn't pay much for the car at all, and did expect having to pull the engine out at some point.

 

I did only run a test on 3 cylinders, didn't want to break my heart anymore today

More investigation required IMO before shelling out to rebuild it. Esp if you've only tested half the engine. If you had less than 100psi on all cylinders I'd expect blue smoke on over run and probably grey smoke on idle as well due to excessive blow by.

Be well worth you having the car health checked by an expert in these cars.

Edited by Stephen

It could be ur meter reading all low not necessarily cylinder low?

Could also be how you tested the cylinders.

You haven't mentioned before the engines running badly, so why the test?

Art

 

- - - Updated - - -

 

It could be ur meter reading all low not necessarily cylinder low?

Could also be how you tested the cylinders.

You haven't mentioned before the engines running badly, so why the test?

Art

  • Author

Hi Art,

The engine winds over very quickly, and does sound like it has lost alot of compression over the years. The engine runs fine really, a tiny bit of blue smoke when you set off after it's sat ticking over from cold, but nothing really. It's reasonably clean exhaust gas wise.

If it runs ok Eddie I wouldn't worry too much about ur testing.

Till you have it serviced.

Do a leak down test will narrow it down for you.

 

Jeff

 

Sorry for my ignorance, but what exactly is a leak down test?

Sorry, no hi jack intended.

  • Author

The reverse of a compression test really, where you pressurise the cylinders with air and see what leaks down past the pistons

You do not mention the year of the car, this can have an effect on compression tests. Early Zeds had a different design head than later ones which resulted in the valve seats wearing badly and causing a loss of compression. The problem is so bad that the only answer is expensive machining or secondhand heads from a later car. The heads are coded via the casting mark but only visible when actually off the xar.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

Recently Browsing 0

  • No registered users viewing this page.

Important Information

Terms of Use

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.