Welps...I posted about tearing my engine out and the dumbazz I was (once I figured out why) in an earlier thread... https://www.rx7club.com/3rd-generation-specific-1993-2002-16/problem-tranny-stuck-engine-423758/

And I've now stripped the engine down to just the bare block...and came upon something very interesting. Those of you that have read my posts before know that my engine pretty much failed, and my compression was 80F/60R with a compression check after about 5000 miles of use after being rebuilt. I had the oil passages widened and I think the water, too, along with a mild streetport.

Now, before you take a look at the pics, please remember that I had EVERY single hose and tube replaced during the rebuild...and upon inspection all of the hoses were still in great shape...some of them looking just as new as when they first went on. I spent a TON of money refreshing everything from the oil metering lines, to getting my injectors cleaned and flowed, to replacing anything that looked bad or needed replacement.

Anyways...today I finished stripping the engine down to the bare block, and I took a few photos along the way. We inspected the apex seals, turning each one by one, looking at it, and listening for scraping, along with the block, and although the seals look fine, we noticed what seems to be a leak right along where the rotor housings bolt together. There was some serious rust and deterioration of the block...and it looked like it was leaking plenty.

Basically, once we got the right side all disassembled...we noticed this:







What do you guys think?

I know there's a coolant line up and to the left of the first photos...but we checked that, and it was locked on tight with no discernible leaks. In fact, it was on so damn tight, that I ripped the thing trying to get it off with a screwdriver. The area is obviously severly rusted and deteriorated, and seems to be concentrated in the edges between the rotor housings. Do any of you think there could be some correlation between this and the engine failure?

I'm not an expert, but this seems strange, because it looks as if there was standing water inbetween the block and the part where the UIM connects, too. I'm not an expert, like I said, so I'm looking for advice from you guys. Thanks..

Here's some more pics of it stripped...

 

I'm wondering if something's wrong with the coolant seal up in that area of the rotor housing. The weird thing is that doesn't look like dried coolant - it looks like ancient, nasty coolant. Were you running good ol' green coolant and water? Was there any crud in that area - dirt, grit, etc.?

I have seen all kinds of sand and crap build up in that area over time - that's normal. You get sand blown into the engine bay through the radiator, and it ends up collecting in dead spots in the engine bay.

You'll know lots more when you tear the motor itself down!

BTW, I have seen the throttle body coolant line from the back of the block to the TB have pinhole leaks, but that was on an old TB line, not a nice new Mazda part.

Dale

 

Nopes...no crud, no dirt..not much of anything. And there's no build-up on the rest of the block. You gotta remember..this thing was perfectly new about a year ago...absolutely spotless. I just find it peculiar that there was water build-up in only this section of the engine and no other rust anywhere else.

As you can see...there's no severe build-up anywhere else on the block. Just some minor grease and dirt. No powerwashing has taken place since the before and after the removal.

 

Most likely that was just a puddle of water sitting there and rusting.

 

That wouldnt be a coolant seal. I've almost never seen failed OUTER coolant seals, which is what that would have to be to leak externally. Plus, it wouldnt leak there...it'd probably leak along the lower half of the engine, because gravity would pull the coolant down. IT's a million to one shot that a coolant seal would cause that.

Plus, coolant (antifreeze) dries with a white crusty texture...not rusty like that. That was a puddle of straight water that sat there. Where the water came from, I have no clue. The only place it *Could* have come from is the throttlebody coolant line you spoke of ripping. It's possible to have those small hoses on very well yet still have a minor leak...not enough to trigger overheating or a lot of loss, but enough to form a puddle over time.

Perhaps you washed off the engine and some water got pooled up there? Not very likely, because the engine temps will burn off a puddle of water collected there in a matter of an hour or 2 max...I've done it before. That signals a consistent, replenishing flow of water to that spot.

 

Did you ever wash your engine with a carwash pressure washer or similar?

 

i think it could be a coolant seal because the rust is sprayed on parts that dont rust like if the car was started and water leaked then the puddle caused the plates to rust and then tha car was started again and the leak splashed the rusty puddle water, i need to go to sleep

 

No wonder your engine failed, you used a fram oil filter!



Sorry, couldn't resist. Good luck on your rebuild.

 

double post

 

That is freaky-weird indeed!

I mean....I don't see how this could have possibly been coolant from the engine. I agree with everyone else here that it had to be some sort of water accumulation. But so much rust in so little time???? I've seen 20 year old engines that didn't have that sort of rust on them!

 

If memory serves, the rotor housing is aluminum so it wouldn't rust like that but the itermediat and side housing are cast iron so the rust is most likely from those three. The location where the rust is would have been a nice little pocket when the exhaust manifold was attached, which would hold a pool of water indefinitely if the engine wasn't hot.
Now for the theories, someone had already mentioned washing the engine bay, if the car wasn't driven afterward for a few days and this was repeated over time, it could be the reason. Another possibility is the combination of vented hood, outside parking and rain. I see quite a few rust spots on the picture of the other side of the engine as well. There must have been a good bit of water in your engine bay on multiple occasions.

 

ArchangleX, you didn't mention how long the car has been sitting not running. Also you are in Hawaii, salt in the air there...

That isn't really much rust at all, it is barely even tinted orange. When things REALLY start to rust you get thick brown flakes not just a little bit of orange powder. Also like Trexthe3rd mentioned there is rust on the front iron too, I think it just indicates you are in a place where things rust. What did the polished parts look like?

Don't forget to pull ALL the things off the engine, I see the crank angle sensors, oil filter pedastal, fuel rail, nuts and bolts. Those types of things get lost at rebuilders, just give them the bare block.

 

You seem to have some light rust on all the exposed iron parts of your engine. Do you have a vented hood and is your car exposed to a lot of salt air?

 

That was a relatively small amount of water that leaked because there are no rusty drips running down the side of the engine. If you had a vented hood, it could very well be rain.
I don't really believe it is likely there is any connection between the rust and your engine problem. I'm going to predict you will maybe find some problems with one of the seals when you open it up. The big question will be what caused the seal failure. 5,000 miles to a rebuild just isn't right, especially with those compression numbers. What, out of curiosity, were the compression numbers after the rebuild?

 

I know my block had a puddle of fuel sitting there from the pulsation dampener. Wouldn't explain the rusting though.

 

another vote for plain water from an external source

 

Okay...thanks for the discussion...sorry for the late reply...I've been partying with Ueo at Drift Session.

Anyways, to answer a few questions...I don't have a vented hood, I haven't powerwashed the car (as I said earlier), and I haven't touched washing the engine bay for about a year. Granted, I lived in the UK for awhile...but that area of the engine doesn't get soaked with water unless you open up the hood and allow a deluge of water to cover it. Which I haven't done.

I guess if it was the coolant line...then as mentioned earlier, I guess it would be covered in that white crusty crap...which I always thought was because of not using distilled water in your coolant...maybe I was wrong about that.

Jeff, the polished parts were still bright and shining...I think maybe the rust could have been from being transported across the ocean to Hawaii from the UK, etc...but that wouldn't explain why it had such a huge amount of water collection in that area and only in that area.

By the way...I wasn't done with the engine at that point. It's been completly stripped now, although I was asked to leave the fuel rail attached because they think the injectors need to be cleaned and flowed. Ahem. I kinda said that had already been done.

Anyways...I'm actively searching for an engine block here in Hawaii to practice and work on, because I'm through with having other people working on my car. From now on, I'm doing it my damn self...because I don't have to worry about the trust issues...and getting ripped off. It's just too much money, and too much of a pain in the azz.

 

I didn't do a compression check after the rebuild...unless turbojeff did. Jeff?