Audiophile426

I bought an '88 Turbo 2 this spring and I am just now getting some time to work on it. It had an exhaust leak (near the turbo) when I bought it but that was the only obvious flaw other than some minor dings and scratches in the body. I drove it for a couple thousand miles this summer before I had a chance to fix it.

When I took the turbo off it was quite clear what caused the leak.


Unfortunately there were a lot of other problems too. First off a couple of bolts broke off when I was disassembling things. One in the turbine housing and one in the exhaust manifold. The manifold flange near the leak was eroded and cracked and there were additional cracks, the biggest of which being near where the cross section changes from the engine flange to the turbo flange.




The bearings in the turbo didnt spin nicely either and the shaft had a lot of radial play. The turbine housing was cracked in several places too.


So my hopes of a simple change a gasket and be done kind of fix were gone. I ended up rebuilding the turbo, replacing all the gaskets (with the super expensive Mazda parts), welding some of the cracks (tho not many), digging all the broken bolts out, fly cutting the manifold flange, and replacing most of the hardware.









So has anyone else had so many problems with cracked exhaust parts?
And, what do you think the chances are that they are going to cause problems in the future?
And, what caused them? Is this an indicator that the engine has been abused?

I cant afford to replace the parts or fix all the cracks so I'm hoping that it will hold together for a little longer. I drove the car today and it is much much nicer to drive. I had never heard it without the exhaust leak so i was surprised at how quite it is. It also seemed to have much less turbo lag but that could just be perception. All in all I'm happy with the fix. I just hope it lasts.

RotaryRocket88

iTrader: (7)

After 25 years of heat-cycling it's really common to find some cracks in the cast pieces. I've had 5 or 6 stock turbos over the years, and the higher mileage ones all had cracks in various places. The best ones were from low-mileage j-spec engines, but unless the cracks are large, I wouldn't worry.

That blown out gasket would definitely have a noticeable affect on how the turbo spools. Since it's pre-turbo, some of the exhaust energy wasn't making it to the turbine.

Also, I hope you didn't purchase the turbo rebuild parts (ie journal bearings, thrust bearing, piston rings, etc...) from Mazda. If they even sell them. The HT-18 can be rebuilt with generic Garrett parts. G-Pop Shop :: quick links Rebuild Kits :: Hitachi Turbo Rebuild Kits

Audiophile426

Yea thats kind of what i expected. It certainly seems much better now. Also I did use the kit from G-Pop Shop. It seems to be working well so far.
Thanks for the reply.

Audiophile426

As a quick follow up. I have a little more time on the car since the rebuild and it is still running very well. I took it to a drag strip and ran a 14.818. That was a little quicker than I was expecting so I was pleasantly surprised.