813KR$

I have about 2000 miles on my fresh rebuild and it just started to act like coolant is leaking into the combustion chamber. 1st sign was my add coolant light would come on and off, and pressure build up with bubbles from the rad. What could have created this problem in your opinion?

85rotarypower

Mabey already warped irons were used in the rebuild? either that, or you have a piece chipped out of the o-ring seal area or the engine was overheated.

bstrange99

There's a chance that it's intake gasket related. Check the bolts. It's a rebuild, so you may need to loosen, then re-torque. If that doesn't help, pull the intake and inspect the gasket and o-rings.
Good luck

-xlr8planet-

iTrader: (3)

when o-ring related not sure if it builds up pressure on the coolant system

trochoid

iTrader: (6)

Compromised inner coolant seal. You won't know for sure until you tear it down.

steve84GS TII

No hard running when its cold,right?
Unless your boosting more manifold pressure than the cooling system operates at,an intake O-ring leak will not over-pressurize the cooling system.

Did you use new rotor housings?
This is probably unlikely,but Ill share a similar experience I had with my rebuilt engine....

My S5 build up was done by Mazdatrix,and included new rotor housings among other parts. After a short time,I started to loose coolant even though I had not overheated or even boosted it much yet.I went through the usual checks while communicating with the builder at Mazdatrix.I tried everything to track down the issue,but it didnt seem to make sense.When all else failed,I pulled the block and took it back to them.
Upon teardown,it was discovered that the front rotor housing had a casting void that had been filled and smoothed with epoxy......JB weld,basically!!
Since that stuff doesnt like heat,it had broken loose and allowed coolant to leak past.Theres no doubt about the housings being new,and apparantly this is standard practice for Mazda when they produce new/replacement housings!!I couldnt believe it either,but John took care of me and rebuilt and broke in the engine at no charge to me,he even started my warrantee over again. Almost 5 years and 40K miles later,its still running like the day I put it (back) in!

813KR$

No hard running at all. Old housings (thats how the chiped edges on housings come in play), never over heated.

Iam using an autozone no pee hole bypass, I was worried that it may let the cool coolant in the engine too abruptly, resulting a warped front housing? When purchasing this part I couldnt find one with the bypass, so I ASSumed it had some kind of internal bypass, which I havent found after closer examination. after the fact!

Also like I mentioned above I have descent looking used housing, but there are small chips on the edge, where the side plates seal againt the housing, basically where the corner peice rides.

813KR$

If the side plates were warped, shouldnt the problems have started earlier? I would think if they were warped from day one of the rebuild it should of leaked since day one? no?