wesmcbride

iTrader: (2)

I came across 2 problems while tearing down my engine. What types of noticeable symptoms while driving would be from:
-Chrome flaking
-Damage from bad thrust bearing

I am trying to confirm that one of these was the reason behind my rebuild and that it wasn't something else that I missed.

Thanks.

rxtasy3

iTrader: (2)

i think with that much chrome missing would result in low compression.

bad thrust bearing could result in too much end play, maybe resulting in a slight noise that could be mistaken as w/p bearing going bad. and would probably get louder when depressing the clutch.

wesmcbride

iTrader: (2)

The problem I had was when I was in 4th or 5th gear, if I went above 3K rpms it would begin to make a rapid taping noise and lose power. I would let of the gas and get it below 3k and it would be good. It sometimes did this when I would get above 6K rpm at the lower gears.

Jeff20B

iTrader: (13)

You most likely have an 82 or older engine with the low volume oil pump. Get a high volume from any 83-85 beehive engine.

j9fd3s

iTrader: (3)

the chrome flaking is normal wear, your housings are actually better than average.

the pitting on the thrust bearing is a bit weird. like jeff says it might be an oiling issue, how did the bearings look?

wesmcbride

iTrader: (2)

The bearings looked fine, but I got new ones anyway. They all rolled free and appeared to have no flat edges.

I have an 82. So I'll look into upgrading the oil pump. You guys are awesome.

wesmcbride

iTrader: (2)

When comparing the oil pumps between the two, is there anything visually that would identify them?

Jeff20B

iTrader: (13)

Yes. Housing size is thicker and the "gear" inside is thicker. Low volume = 12mm, high volume = 17 or 17.5mm.

wesmcbride

iTrader: (2)

Thanks. I was thinking the 17.5 mm was the larger one, since that is the size most places sell for up to 1985.

j9fd3s

iTrader: (3)

all the 83-85 cars should have the big pump.

steve84GS TII

Thats what I was thinking.
It may look bad,and while it could be better,Ive had/seen engines with worse chrome flaking that ran fine.

wesmcbride

iTrader: (2)

The housings only have 80,000 miles. I picked up a set of housings with almost no wear.

Jeff20B

iTrader: (13)

Yes it's an oiling issue. Mazda solved it by going to the big oil pump. This cured the tendency for thrust assemblies to self destruct and it lengthened rotor housing life a bit as more oil was availalble from the OMP. Other things live longer because of this; oil pump chains stretch less, stat and rotor bearings show less copper, apex slots in rotors get less V shaped.

Mazda solved their oiling issues. Then for some reason (bean counters) the S4 NA got a low volume pump again in a new larger "frame" size. Always swap to the high volume T2 unit if you've got an FC engine.