RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   Rotary Car Performance (https://www.rx7club.com/rotary-car-performance-77/)
-   -   Engine Builders.. Need your opinion! (https://www.rx7club.com/rotary-car-performance-77/engine-builders-need-your-opinion-1028435/)

GTR 03-05-13 11:15 PM

Engine Builders.. Need your opinion!
 
8 Attachment(s)
I recently bought a non-running T2 and it had low compression on the rear rotor - 50psi. I tore apart the engine today and spent most of the day at work cleaning while working on other cars.

I think this engine's just been sitting for a long time since it hasn't registered for over 2 years.

I haven't measured anything yet since I wasn't sure if I should be using these parts.

The rear rotor has score marks and the e-shaft has some scratches but nothing i can catch my nail with.

Thank you for your time.


Attachment 679989
Attachment 679990
Attachment 679991
Attachment 679992
Attachment 679993
Attachment 679994
Attachment 679995
Attachment 679996

GTR 03-05-13 11:16 PM

7 Attachment(s)
Attachment 679982
Attachment 679983
Attachment 679984
Attachment 679985
Attachment 679986
Attachment 679987
Attachment 679988

GTR 03-05-13 11:17 PM

8 Attachment(s)
more pics.

Attachment 679974
Attachment 679975
Attachment 679976
Attachment 679977
Attachment 679978
Attachment 679979
Attachment 679980
Attachment 679981

GTR 03-05-13 11:17 PM

10 Attachment(s)
Attachment 679964
Attachment 679965
Attachment 679966
Attachment 679967
http://i1297.photobucket.com/albums/...ps1964cc98.jpg
Rotor in question
Attachment 679968
Attachment 679969
http://i1297.photobucket.com/albums/...ps821c7b3d.jpg
Attachment 679970
Other Rotor
Attachment 679971
Attachment 679972
Attachment 679973

peejay 03-06-13 12:09 AM

Waste of a gasket kit. I've built 120+psi compression engines with far worse looking components.

How long/hard did you run the engine before checking compression?

GTR 03-06-13 12:31 AM

the engine didnt run at all.

I did a compression test with a valve removed -
front rotor did 30 - 30 30 psi jumps
and rear rotor 30 - 10ish - 10ish

did an overall compression test
front was 85-90
rear was 50

peejay 03-06-13 05:38 AM

The engine I won last year's divisional championship with did something like 40psi front/25psi rear.

I don't think any of the hard parts are a problem. Probably just stuck seals from sitting. Shine up the rotor housings with penetrating oil, Scotch-Brite pads, and elbow grease, clean them off EXTREMELY WELL again, do the usual measuring of all seals (length and groove clearance) and see what you find.

j9fd3s 03-06-13 10:02 AM

i see the stamp from the Mazda rebuild facility in the 90's, which is probably why the bearings look new and nothing else does.

GTR 03-06-13 11:00 AM

Thanks peejay. I'm cleaning the parts now.

J9fd3s .. what exactly does that mean ..
Means they just put bearings, seals and called it a day ?
It did have 3 piece seals in there.

j9fd3s 03-06-13 01:10 PM


Originally Posted by GTR (Post 11397531)
Thanks peejay. I'm cleaning the parts now.

J9fd3s .. what exactly does that mean ..
Means they just put bearings, seals and called it a day ?
It did have 3 piece seals in there.


that means it, or that rotor housing was put in a Mazda reman at a time when they did that stamp, before 1998.

i see that the bearings are new, but its hard to say about anything else.

GTR 03-06-13 05:16 PM

The rotor has score marks and I can catch my nail on. It's on the compression side of the rotor near the apex seals. It's only on the rear rotor.

GTR 03-07-13 12:01 AM

2 Attachment(s)
Rear Rotor ..
Attachment 679917
Attachment 679918

Should I just replace it?

jaggermouth 03-07-13 12:16 AM

I'd use it, but I'm no pro

GoodfellaFD3S 03-07-13 12:39 AM

You're referring to all those nice straight lines as 'scoring?' That's normal. The rotor is fine, unless I'm missing something..... do the apex seals clearance ok?

RotaryEvolution 03-07-13 08:55 AM

the rear rotors usually had a grainy surface, i never could figure out why. i believe mazda had a reason for this but what it was is a mystery.

everything looks fine but i would probably run some fine emery cloth over the e-shaft.

j9fd3s 03-07-13 09:56 AM

having sold a bunch of new rotors, that "scoring" is when they should have changed the bit in the rotor mill... if you order new parts, you get an occasional rotor that's like that, and the rest are smooth.

RotaryEvolution 03-07-13 11:45 AM

almost all turbo engines have a smooth front rotor and a rough machined rear rotor though. but you're probably right, it's just coincidence. they appear mainly on series 5 and 6 which also have the machined compression pockets.

GTR 03-07-13 01:48 PM

4 Attachment(s)
So I finally finished cleaning the parts and I did run scotch brite through the shaft, rotors, and rotor housings.

Attachment 679830
Attachment 679831
Attachment 679832
Attachment 679833

j9fd3s 03-07-13 01:59 PM

i'd just rebuild that, it looks pretty nice

RotaryEvolution 03-07-13 02:17 PM

looks like a runner to me.

ArmyOfOne 03-14-13 01:45 AM

Winner

RotaryEvolution 03-14-13 01:36 PM

looks familiar to some parts i came across on ebay. heh

GTR 03-14-13 01:49 PM

I actually sold the rotors. My plans changed. Most of the engine parts has been sold.

killahrx7 03-14-13 02:25 PM

Reason why the engine had low compression could be from carbon build up or like others mentioned stuck seal. Recently opened two 3 rotor engine that we bought as core, they were perfect. Nothing wrong inside.

ricardo.benin 03-24-13 11:10 PM

I would get a nother rear rotar housing


All times are GMT -5. The time now is 11:26 AM.


© 2024 MH Sub I, LLC dba Internet Brands