Maninder

So from my previous thread my engine has low compression

Rotor #1 5.6,5.4,5.8kPa @222rpm
Rotor #2 4.7,5.8,6.1 @259rpm

the Mazda tech told me to get them to do a carbon clean (cost was around $200) I wasn't sure if it was worth it by seeing how low the compression already is do you guys think it would make a really big difference? If it is just carbon built up in the engine would my engine get back to normal compression? or has the damage already been done?

Harlan

iTrader: (3)

Doubtful it will help. Is the car under warranty?

poacherinthezoo

Looks like bad/worn apex seals on rotors 1 and 2, and a worn out side seal on rotor 2 as well. I don't think a carbon cleaning will do this engine any good - it's pretty far below "failing" on all faces.

You also have the units as kpa - but based on the numbers you have listed I think what you meant was kg/cm^2 ?

Interesting amount of variability in starter cranking speed.

nycgps

iTrader: (1)

just decarb it with water, Rx-8 has a LOT of carbon build up, it might bring the compression back up by a bit.

RIWWP

iTrader: (2)

If you are going to replace the engine on your own dime, or if you are just going to get rid of the car anyway, then it is worth seeing if a decarb would improve anything, since you don't have anything to lose.

IF you opt not to do the Mazda decarb, then your best bet is to ingest distilled water at a controlled rate while the engine is held between 2,000 and 3,000rpm. At least a gallon, perhaps 2. Seafoaming where you just let the seafoam sit does exactly nothing against carbon in the engine. Seafoaming where you ingest seafoam into the engine while it's running is exactly as effective as distilled water, while costing 80 to 100 times more per ounce.

SayNoToPistons

iTrader: (8)

Also keep an eye on the catalytic converter (if applicable) when decarbing with the engine running. That is if you bother with decarbing.

JamesD31

So, when my engine died they told me I had to get it carbon cleaned out before they could tell the warranty company that it was the engine - aka pulling my chain for some money.

After doing that, my car was not able to run at all before it kept dying randomly while driving it - be prepared. The carbon build up is probably what is keeping the engine running with those types of numbers.

CRAZ8

Decarbing using distilled water is the same as Seafoaming?

RIWWP

iTrader: (2)

If you ingest it while the engine is running (as shown earlier in this thread), then yes, it is just as effective.

nycgps

iTrader: (1)

not only its just as effective, it's cheap (dude, it's water) and there is almost no ill side effects.

As for the CAT, don't worry about it, keep an eye on it and u be fine mostly.

Remember to inject oil after the cleaning job, otherwise your compression will look like complete **** (steam gets rid of the oil film really well), after you inject (or just vacuum thru the ports) , the numbers will go up

but u should ALWAYS do an oil change after the job.

CRAZ8

Thanks for the info... Mazda has agreed to replace my engine.)