scathcart

I had a 6000 mile rebuild fail on me with the characteristic coolant seal problems; excessive, sweet smoke in exhaust, bubbles in coolant neck, overflow canister filling very rapidly.
So, today I took the engine out and dissassembled it, and I could not find anything wrong.
All of the water seals (aftermarket teflon encapsulated) were in their positions without being pinched, and all were in good condition, even reusable. The water seal groove had no cracks, and I could not find any pitting of the seal groove. There was no visible pitting around the spark plugs in the water jacket. The rotor housings both had a tolerance of .002", and the irons were all straight-edged to .002".
The tension bolts felt a little loose, but I had torqued them to 30 ft-lbs, and today verified that indeed, my torque wrench is correct (at 80ft-lbs).

Does anyone have any ideas? I am scratching my head here. Normally coolant seal failure is so easy to diagnose upon dissassembly, and I don't want to reassemble it until I know what is wrong.
I might have the rotor housing magnufluxed (well, dye-tested; I don't think you can magnaflux aluminum) in hiopes of finding a pinhole, but other than that, does anyone have any ideas of what else to possibly check?

Could it be the tension bolts vibrated loose? I had used engine oil on the threads when reassembling, no loctite. Loose tension bolts is my only idea, but I figured I'd at least be able tell where the combustion gases were entering the combustion chamber.

Thanks for your input,
Sean Cathcart

BigTone

My rebuild failed on me with only 100 miles, however I had a cracked center housing, and half of my tension bolts were loose. For mine, I am thinking that the loose tension bolts led to the center housing to be cracked. Now I rebuild my engines myself, so I can only blame myself if something goes wrong.

Good luck

geargrabber

Steam in the exhuast definately points to water getting into the combustion area. I had the very same problem and the failure point was one of the irons ( a segment of the water jacket seal groove wall broke). Ive never used teflon aftermarket water jacket seals, just the orange ones.


How much steam is there? Mine had a bunch... if i held a piece of glass up to the exhaust,(other material would work) water condensation would build up and start dripping water.

Well anyways, after i tore down my engine and replaced that bad iron side housing (front side housing) i didnt check the new eccentric shaft end-play... the engine lasted only six hundred miles Now the engine makes a horrible rattling noise, ive checked the all the things i could without taking the engine back out of the car -

exhuast sleeves
front and rear main bearings
stuff in the front hub
even took off upper and lower plenum

so the conclusion is the bearings on the rotors are tore up... (copper flakes in oil pan), which i can only think would be improper e-shaft play.

scathcart

Classic coolant seal failure, caused by overheating. Not the problem here, but thanks.

I can't find a thing wrong, or where the coolant entered gthe combustion chamber. This is driving me nuts.

Sinful7

You could have a blocked radiator?
If you do it will heat up and spew coolant out of the over flow bottle.
You could have the radiator flushed.

scathcart

That doesn't explain the steam in the exhaust, or why another engine runs fine when put in its place.

Cheers!

There is a coolant line going to the turbo, maybe the coolant is leaking into the exhaust stream via the turbo?

mazdaverx713b

iTrader: (91)

i was thinking turbo coolant line myself. then maybe one of the housings were not lapped correctly?.

fcturbo2

When i built my TII engine i torqued it down to 35 ft/lbs. My friend that builts rotary race cars told me that he torques the tension bolts to 40 ft/lbs. If i were you i would've atleast performed a leak/pressure test before assuming that it was the engine.

Cheers!

on second thought, scath did say there were bubbles in coolant neck and overflow canister filling up...

I don't know then... good luck

scathcart

Leak pressure test on a rotary? The engine won't naturally hold compression, so a compression leak down test is worthless.

Pressurizing the coolaing system as a test just makes for a lot of smoke in the exhaust.

And lastly... on a spare engine, eferything else ran fine.

I KNOW it was the engine. Now I just need to find out where.

The side housings wre not lapped, but were well within specs.

I am magnafluxing the rions and dye-testing the rotor housings. After that, I will just reassemble it.

Scalliwag

Were either or both sets of spark plugs extremely clean? That would verify if the coolant was actually going into the rotor area and if it is one side it narrows down the areas you need to inspect by 1/2.
If all plugs had carbon (and rotor faces too) then look to the turbo side for the problem.
It is a lot like when you blow a head gasket on a piston engine. Any cylinder that took water is always really clean.

RotaryResurrection

iTrader: (8)

Be sure to use sealant/hylomar on each side of each water seal. To begin with, I used only hylomar on the iron side of the coolant seals, and none on the rotorhousing side. Then one time minor pitting on a rotorhousing caused just what you have...a bad motor. I re-rebuilt it, this time using hylomar on both sides...it fixed the problem and the engine runs fine to this day. The more I thought about it, though, I figured the water could eventually wash away the hylomar from the rotorhousing side if there were pits there, so i went to using ultra black sealant. Then, out of simplicity, I went to using the sealant on both sides of the seal.

The sealant is just an extra measure of protection against leakage, especially good when reusing rotor housings that have an imperfect surface.

As a side note, the use of the sealant I like seems to have the added benefit of overheating protection. Due to a stupid mistake, when I put the motor into my convertible this fall, I pegged it on the H (s5 non linear gauge) with only 3 miles on the engine. A few thousand miles later it is good as new, and has never lost a drop of water. I don't think that could be said of any other engine if you took it to H on teh gauge (especially the s5 which are known not to move at all unless they're really hot).

scathcart

Unfortunately, I did not receive the engine with the spark plugs installed.

It's not the turbocharger; the turbocharger works perfectly on another engine.

scathcart

I coat all my o-rings with hylomar, and put a good layer of hylomar in the water seal groove.
Do you suggest also using something such as RTV?
I was not able to find any pitting asy of yet.

RotaryResurrection

iTrader: (8)

I still use hylomar as an assembly aid for certain o-rings and parts on the engine, but I use just the rtv/seralant for the internals now. It is ultra black, made by permatex if I am not mistaken. High temp, black (not ghetto blue, copper, or orange), VERY tough stuff once dried.

I'd bet you just didn't get something sealed up in there as far as the coolant seals. IF you can, clean them up really well and reuse them, this time with a fair amount of sealant on both surfaces. Or, you may want to get new ones, no more than they cost, just to be safe.

VERY rarely do you see a crack in the rotorhousing or iron cause this.

Scalliwag

Just be sure to use a very thin and fairly even coating. You can do more harm than good if you go nuts with the sealants.