Hi Guys,

Wondering if any of you all can help me (Please)!

I have a 1988 2nd Gen RX-7. The car was supposed to have had a rebuild around 5000 miles before I bought the car.

Anyway, currently the car starts from hot and cold first time and holds idle well and consistently at 1000 rpm. However, it does sound a little rough. I used a rotary comp tester and the results are 7, 7, 7 bar compression @ 240 rpm on front housing but rear housing is showing an absoloute 0 compression on the compression tester on both the leading and trailing plug holes.

Would anyone happen to know just what is happening. I have heard that maybe squirting some premix through the plug holes may help!? Anything else??

Any help would be very appreciated.

Many Thanks.

 

7 bar? one bar = 14.5 psi right?

that would mean 101.5 in the front housing.

0 bar = 0 psi.

Are you sure you're doing the compression test correctly?

 

a rotary will run on 1 rotor. just very poorly... ive gotten my blown t2 up to over 100 mph before.. its just like having half the power...

 

Yeah, I am doing the compression test properly. We used two different comp testers and both gave same results.

Someone suggested that seal maybe sticking in the rear so therefore apply some pre mix through the plug holes??

 

Do a simple test. Remove one of the spark plugs in the rear rotor housing and crank the engine [first remove the EGI fuse]. Listen for the compression pulses, like CHUFF-CHUFF-CHUFF. If you don't hear anything like that, your readings are probably correct.

So, you can try squirting some Seafoam (http://www.seafoamsales.com/products.htm) in the rear housing plug hole. Crank the engine a few times and then let it set for like 20 minutes. Crank the engine again and then reinstall the EGI fuse and start the engine. You will see lots of smoke as the Seafoam burns off. Once the smoking passes, do another compression test.

 

Unfortunately, we dont get seafoam here. Would premix oil or automatic transmission fluid (atf) do the same job? Or is Seafoam the same as WD 40??

Thanks again

 

Try Marvels Mystery Oil. Worked great on my jdm engine to free up a seal. Otherwise you could try PB blaster if its a stuck seal (or in your case a bunch of stuck seals). You may also just want to put a spoonful of oil in the rear rotor and crank it over a few times to see if it builds compression.

Edit: I'm not sure if PB blaster breaks down carbon, if your seals are carbon locked. I know it will unsieze a rusted up engine but not sure about carbon. ATF is probably a better choice if you cant get MMO.

 

Problem is, I am not in US so we dont have stuff like MMO and Seafoam and PB Blaster.

Sure, I can get hold of some ATF and WD 40 (http://www.wd40.co.uk/index.cfm?articleid=13)

Apart from that, not too sure. Also what amount of ATF should I pour through the plug hole??

 

I doubt that either of them will do much to remove any carbon particles/coating. There certainly must be a product in the UK that is equivalent to MMO or Seafoam? You can also get a product from your local Mazda dealer that is used to decarbon the RX-8s. I will get you more info and add it to this post.

EDIT: Check out the RX-8 service bulletin at the link below. Your Mazda dealer should be able to order the "engine cleaner" for you.
http://www.finishlineperformance.com...4-08-1924f.pdf

 

If there's no comp. on the rear rotor - its blown. Rebuild time.

You can have a blown engine and the car may still start and run "just fine". But if you compression tested it and found zero comp on one rotor, you're missing some apex seals - or pieces of them.

No magical engine cleaner is going to fix that.

 

had the same problem with my car... except it was the front rotor.
have u driven it? if its slow as **** then yah rebuild it or get another motor

 

if it sounds like a motorcycle then rebuild it. how bout trying to start it without the front plug wires. if it doesnt start then your in some trouble... if you feel needy i can ship you some mmo or seafoam if you pay for everything.

 

hes just in the denial phase my friend and i were when we found zero compression on the rear rotor (all faces) We tried everything we could think of to make it work, neither of us wanted to admit it was blown....

 

Thanks for all the help guys and dean - I may take you up on your offer some day, thanks.

If it's blown then its blown, i'll carry on. However, if something like ATF through the plug holes may help then it would be interesting to see results or if the rear starts showing even any compression. If it's blown then I may aswell experiment.

We do get some "engine flush" here which you pour through the oil tank and then after starting the car for around 20 mins. You do a oil change.

For starters, I want to pour some ATF through the plug holes. Anyone know how much I should pour?

Thanks again guys.

 

Don't waste time putting any fluids in through the spark plug holes. If it's showing zero compression, it's blown.

Try this test:
http://www.aaroncake.net/rx-7/blown.htm