Is an overheated engine worth rebuilding?
 

Hi guys,

I am interested in knowing if it would be wise to rebuild a current engine I have sitting here in the garage. I have a complete shortblock that came from a friends rx-7. Basically given to me as payment for helping with it's removal and installation of a reman. This engine prior to its removal had low compression approximately 85 psi in the front rotor chamber and 100 psi in the rear, so it was running but would be a bitch on startup with constant flooding. Apperantly the engine had also been subject to a split in the plastic ast tank, which I imagine caused the engine to overheat. Amazingly, It did start up and continued to be operable and allowed the car to be driven.The guy didn't know whether it did or not, but common sense tells me it would have. Just wondering what possible damage could have been affected by the overheating. Would the aluminum rotor housings be the only thing I would need to worry about, since from what I hear they are the first to warp. Would the cooling chambers also be affected, as they are made of steel and imagine they would more prone to warpage. Anything else motor wise that I would need to be concerned of?

Also another rebuild question that I had, is are the apex seals ever salvageable? I imagine it would be wise to replace them regardless, since you would be going through all the trouble.
Thank you in advance for your time.

I bought my 90 vert with a badly overheated engine. I had to replace one rotor housing. The other hard parts were fine. Cleaning all of the rust was a bitch.

Definitely replace all the seals, springs, and gaskets. Make sure you look closely at the rotor housings for wear as well as warping. Make sure you use a gauge as detailed in the shop manual.....you cannot eyeball the rotor housings for warpage. My warped housing looked fine to the eye. Also, re: irons, if they are warped, most likely you will see cracking in the area around the coolant o-ring groove, so it will be readily apparent if there is warping.

Hope this helps :)

Well said Rich.

Some reuse apex seals, I don't do it on a daily driver but if the engine only has to last one season and I have some exceptional seals I will.

Ask me! LOL
You'll never know until you take it apart and check its specs.

what sort of problems with a warped rotor housing cause?

who cares? On a performance car why would you waste your money and not replace a warped housing??? If you are going to do something do it right.

You never know until you open it up. ONe thing about waterseal motors, if theyve been allowed to sit for months on end without being turned or lubricated internally to displace the water, there is likely a lot of rust formed that will ruin everything. Check the exhaust ports of any engine you're considering getting to rebuild...other than that, tear it down and see. IF it's junk, put it back together and use it for a reman core.

My vert had been sitting for ~18 months. Gallons of parts cleaner, many cans of PB Blast, and 3 days straight of elbow grease, and everything was reusable. Keep in mind this is on a stock n/a car.

Rich

I have gone through water pumpers that sat for a while that were just JUNK - I ended up throwing out most of the engine.

Sure is tempting to use it as a core for a reman :).

Dale

Here is what you find when a waterseal motor is allowed to sit for a long time:

www.rotaryresurrection.com ---> tech ---> internal engine damage, look at the pics of the rusty parts.

Wow, that is an awesome page. :bigthumb:

Dave