I'm looking at an '04 AT RX-8 at a second hand dealer and the inspection sheet with it says it's above average condition for what it is.

The sheet lists "relative compression test", but it lists 4 numbers between 0 and 100, rather than the 2 sets of 3 numbers which this forum says.

Is this compression test for something else, not the correct test for a rotory engine or is it just another way of doing the compression test? (Note: Neither the dealer nor those who did the inspection are a Mazda dealership.)

Thanks in advance.

 

Are the four numbers labeled in any way?

I'd guess that whoever did the test did not know squat about rotaries, and just put a regular compression tester onto each of the four spark plug holes.

Ken

 

+1, I think they probably did just as Ken states. Without 6 numbers, 3 for each rotor, it's not a valid compression test.

 

A supporting thought...does the sheet list the engine as being a very narrow angle V-4?

Ken

 

I was pondering something similar, a V4 laying on it's side.

 

Thanks for the replies, guys. Sorry I couldn't reply earlier; I had work.

The only copy of the sheet I have available to me at this very moment is a very low resolution picture on the dealer's website so it's hard to see, but I am fairly sure each of the 4 bars (it's a horizontal bar graph) are labelled 1 thru 4. So, bar 1 is labeled "1" and has a value close to 100.

It would be strange if this is not the right test, as it was performed by a franchise of what is likely one of the largest automotive and insurance companies in my country (New Zealand).

Am I going to need to tell the dealer that I need the test done through our local Mazda dealer?

 

Take a look at the post in this thread with my compression sheets attached: https://www.rx8club.com/series-i-tec...7/#post4408673

That is how you need them. If they didn't use a ROTARY COMPRESSION TESTER, then the test results don't mean anything. You need 6 individual scores, one for each face, and at least 1, if not 2 RPM scores (they are usually within 1-3rpm of each other, so just 1 usually works)

And this post in the new owner's thread explaining why a regular compression tester doesn't work: https://www.rx8club.com/new-member-f...4/#post4533733

 

I have read all that new/potential owner thread before, but thanks for confirming it. It's good to see what a compression test sheet looks like too.

I guess I will have to tell the dealer that it is the wrong type of test.

The car has only 37,000 km (23,000 miles) on the odometer. Even so, is it necessary to get a compression test done before buying any second hand RX-8?

 

23k is a tougher call. Under 20k, I wouldn't be all that concerned. 20k to 50k I could easily be willing to ignore a compression test pre-purchase as long as there is a warranty, though I'd still get one done post-purchase as soon as possible just to confirm. There were enough early mileage failures, and enough cars don't have any warranty at all, that I won't ever tell someone to skip the test. Plenty of RX-8 out there are dumped specifically because they have low compression, so the odds of getting a bad one are somewhat higher than people expect.

If the engine doesn't have a warranty on it, I hands-down wouldn't purchase without a test, regardless of mileage.

 

It's a Japanese import, so I imagine it wouldn't have a Mazda warranty I could use here. I will be getting a 2 year mechanical and electrical warranty on the car from the dealer through some insurance company, but you do make the test sound rather important. At least just in case that warranty doesn't cover this specific issue for some reason.

Thanks heaps :D

 

If its not the Mazda warranty then its most likely useless, and since its an 04, Mazda's warranty is long over.

Ask the Dealer what's the cap on each claim, and how many calims are you allowed under the warranty they offering you.

All the best

 

Thanks for the advice. The warranty covers $8k per claim and unlimited claims. But it does state that it doesn't cover faults that were present at the time the vehicle was purchased, so I will have to enquire with the insurance company about whether or not that means faults I knew about or all faults found that were likely there at time of purchase.