ArchangelX

Recently, my car has had a spat of trouble, see here for the full story: https://www.rx7club.com/forum/showthread.php?t=340167


My question is this:

If an engine were to go by fault of it's ancillary components (injectors, fuel pump, hoses, etc.) or the specific tuning or condition of it (lean condition, over-heating, coolant loss, etc.), would the resulting compression of the engine be more or less uneven or would it be a steady number...

Like 60-60-60....or would it most likely be in a more catastrophic state such as 20, 45, 60?

The reason I'm asking is because the rebuilt motor that I had...only accumulated about 5000 miles of relatively sedate driving, yet it now has low yet even compression on all three seals of the front and rear rotors.

I got the following on the front and rear rotor...

Front: 60-65 PSI with three slightly smooth pulses.
Rear: 80 PSI with three smooth pulses.

If it was a fuel or ancillary problem that caused the damage to the engine, and the poor compression, wouldn't the engine give something more representative of a specific, violent, incident?

This was a rebuilt engine with 98k on the odo when it was removed from the car...so it was definetly a tired motor to begin with. I had a compression check done on it at a Mazda dealer before I bought it, and it was definetly on it's last legs. I've checked all the hoses, vacum lines, map sensor, connectors...pretty much everything I can think of in the past day or two, and I just don't see how this problem could have developed. The car has never overheated, has always had full fluids...etc. I'm stumped.

I guess I'll know when the thing is ripped out...but I'd like to know the cause, and why....whether if it was the ENGINE that was bad to begin with, or if it was the way everything was put together, or if something went wrong with the tuning.

ArchangelX

Hello...anyone home?

DaleClark

iTrader: (55)

Really hard to tell. I think tearing down the engine and seeing what the story is will be the only way to know for sure.

If the apex seal slots in the rotor were out of spec, the apex seal could be flopping around a lot, which wears it more quickly. Or, an oil injection problem could cause that kind of damage.

If you're going to be dealing with the shop that built the motor, it might be tricky. Most shops in general don't like to admit they made a mistake, and definitely don't want to pay for a warranty replacement. You might have to fight them on this. I do have a gut feeling the engine is the root problem here, not the stuff bolted to the motor.

Dale

paw140

I recall recently reading a thread about a new batch of Mazda apex seals failing by warping or something. But it resulted in a loss of compression because the seals didn't actually break, they just wore rapidly and unevenly until the compression got really low. Try searching for that. I know one of the threads was on the *other* forum.

ArchangelX

I wish I could tear down the engine, but that would void the warranty. Which really sucks, because I'd like to see what the real problem of this thing is...I read that 93BlackFD went to PR, and took pictures of the whole process. I heard it didn't go very well. I don't think I'd be able to do that...but I sure as hell would like to see what the engine looks like after teardown. I think anyone would.

I was thinking that if it ran outta gas, or detonated, then one of the seals would be pretty messed up, and the other two would be messed up, but just not as bad. It seems like my engine just is..."tired" if you get my meaning...as in it still runs, but the compression is so low, it idles like crap, and dies.

I took it to the hobb shop again, and inspected all of the turbo components, took of the UIM and elbow, checked all the hoses, and didn't see anything amiss. I even played around with the fuel system, but I don't know enough about it to check if it's working properly.

You think it'd be too much of asking for them to take pics of the engine as they tear it down? I don't wanna make them mad. I think Rob is a decent person, and from my experiences so far, he's been a really knowledgeable, helpful person. I'm just hoping he comes through for me, because my situation is pretty crappy right now due to all that's happened...it just sucks that it's gone down this way.

Has anyone else had to deal with warranty work from PR?

DaleClark

iTrader: (55)

Call Pineapple Racing. You're just speculating on what they could, couldn't, would, and wouldn't do - call them and get the ball rolling.

Or, say screw it, spend $2200 on a Mazda reman, and tear the current motor down.

Dale