GTR

iTrader: (6)

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.

GTR

iTrader: (6)

GTR

iTrader: (6)

more pics.

GTR

iTrader: (6)

Rotor in question




Other Rotor

peejay

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

iTrader: (6)

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

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

iTrader: (3)

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

iTrader: (6)

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

iTrader: (3)

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

iTrader: (6)

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

iTrader: (6)

Rear Rotor ..



Should I just replace it?

jaggermouth

iTrader: (1)

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

GoodfellaFD3S

iTrader: (213)

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

iTrader: (30)

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

iTrader: (3)

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

iTrader: (30)

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

iTrader: (6)

So I finally finished cleaning the parts and I did run scotch brite through the shaft, rotors, and rotor housings.

j9fd3s

iTrader: (3)

i'd just rebuild that, it looks pretty nice

RotaryEvolution

iTrader: (30)

looks like a runner to me.

ArmyOfOne

iTrader: (12)

Winner

RotaryEvolution

iTrader: (30)

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

GTR

iTrader: (6)

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

killahrx7

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

iTrader: (6)

I would get a nother rear rotar housing