Valve seals is plausible. My tought running thru my head are ignition. Plugs and packs not burning ----

 

Yes I thought the same thing, valve seals....but in all 4 cylinders?
I'm taking the head off this afternoon once the kids get home from school. (I'm teaching my 2 older kids whatever I can about car maintenance...they start driving in a few years). Last month, they swapped out an engine on a Mazda 626 by themselves, with my guidance.

 

Problem I see here is that on all 4 cylinders. Pretty hard to judge from that because well, its all 4. If it were 1 then yeah. Also I don't know if your car is like others. When y removed the pcv hose , was it from oil filler that connects to intake throttle body area?. May be building too many gases in block and pushed oil thru that hose. Just throwing info out that is all

 

Yes...that's the problem I'm having with this also. It's on all 4 cylinders which is very odd for valve seals going bad.
I removed the pcv house that connects into the intake manifold at the IM, and capped the port so I don't have a vacuum leak. I also removed a breather hose that vents into the intake hose near the MAF sensor. When I ran the engine with both hoses disconnected, I did not see much blow by, not more than usual anyway, so the rings are not creating too much pressure in the crankcase.
I guess if it's not the seals, it could be the head gasket or the oil rings...but again, in all 4???

The oil, and a lot of it, is getting into all 4 of the cylinders somehow. In all my 20 years of tinkering with cars, I have never seen this.

 

Just looked at a cylinder head. Nothing really could go wrong besides valve seals. UNLESS!!!! Your cams are shot!!!

 

cyl. head could be cracked too, I won't know until I take it out.
Why would the cams contribute to the oil problem? I pulled the valve cover off, the cams look fine, the oil return passages are not plugged at all. There is no sludge in this head...in fact, I'm surprised how clean it is in there.

 

Bad timing is wat im getting at. Could be a tooth or 2 ahead and leaving intake valves open just pondering here lol. Any clues found yet?

 

if it was a tooth or two ahead or behind, it would not idle as smooth as it does. I'm about to pull it into the garage to start on it. I had to do some maintenance on my daily driver this morning.

 

Have you removed your cat to see if it's all broken up?

 

Today I started tearing down the engine. I removed the exhaust manifold and looked inside. The inside material is broken in two, see pictures below. I drained the oil and there seems to be a white/tan film on the surface of the oil. Is this the ceramic material from the cat? So should I just break apart the honeycomb material and hollow this thing out? If I do that, what do I do about the O2 sensors, will a spacer in the (upstream or downstream) prevent a CEL?

I then removed the battery, alternator, the engine mount on the passenger side, engine mount on the front, coolant reservoir, I removed and put aside the fuse box, and I started to remove the timing cover. I also discovered this engine has a timing chain instead of a timing belt. I checked the timing marks and they are ok, it has not jumped a tooth, which I suspected all along. The engine block on this thing is in 3 pieces, which makes it a real pain in the butt to remove the timing cover. I'll spend some more time on it tomorrow and post more pictures.

In the meantime, if some of you can chime in on my questions above, I would appreciate it.
John

 

You can hollow out your cat as a temporary fix. If you have to pass an emissions sniff test, you will no longer pass. You can replace the manifold with a header as many members have done with success.

Using an 02 spacer will work to keep the light off, but it has to be positioned on the rear 02 to have any effect.

 

There is no sniff test here, just a CEL check.
I have several questions still:
1)So is the pictures of my cat what many here refer as pre-cat failure?
2)Is the excessive amount of oil in the cylinders due to the rings caused by the pre-cat failure or could it still just be the valve seals?
3)Should I rebuild this engine or will the problem just come back again?
4)If I hollow out the cat, then re-hone the cylinders, install new rings, rod and main bearings, valve seals and head gasket, and completely clean the engine block, will it be ok? Or should I just get a used engine. The least expensive engine I've found is $1200, but I won't know if it's contaminated too until it's too late.
5)Instead of getting a header, what if I just hollow out the cat completely and put the spacer in the downstream O2 sensor, then get a universal cat further down in the exhaust just before the muffler to be legal in case I sell the car? Will that work?

 

1) Yes.

2) Most likely piston ring and cylinder wall damage caused by your dead cat. Could also be a combination of both, but given the history of this issue, I fully suspect ring damage.

3) If you decide to rebuild this engine replace the precat/manifold with a header to avoid this converter issue, but see #4 first.

4) If you were to find a low mileage QR, make sure you get at least a 90 day warranty and drop the cat first thing for an inspection. I'm sure you'll find a used engine will be cheaper then the complete tear down option.

5) If all you have to do is pass an OBDII scan then placing a converter further down isn't necessary. The 02 sensor spacer should do the trick.

 

^^^ agree on all 5

 

I can't tell you how much damage has been done, so I can't really give you a clear answer as to wether you'll need to bore the cylinders. Considering you have good compression you could very well get away with just replacing the rings.

If you're prepared to bore out your cylinders, start by trying to locate an oversized set of pistons before you do anything. I don't know how readily available they'll be.

There is nothing wrong with hollowing out your precat and leaving it that way, imo, but a lot of guys will argue it will give you a tonne of air turbulance which will adversly affect your performance. A header cleans it all up and gives a small bump in power as well. You're right though, it is essentially the same as installing a header.

The only reason I recommended getting an engine with 90 day warranty was so that after installation if you have low compression or you drop the manifold and the cat is destroyed, you would have a little recourse. Some guys will buy blindly from a wrecker and are dumbfounded when the engine is toast and they are stuck with it. Just protect yourself is all I'm saying.

 

Those are all great points.
Do you know where I can find a header for it?

 

http://www.facebook.com/markspecv.markracerx

Here is MarkspecV's facebook page. I don't have his email address, maybe someone can post it up for me. Mark includes everything you need including spacers and will help you in any way possible.

 

Well, the head is off! It's still not entirely clear to me how the oil is getting into the cylinders. The valves were all wet and coated in oil (see pictures), so were the top of the pistons. The cylinder walls look great with no scoring of any kind, and there is just a very slight ridge near the top as expected with 100k miles.
Oversize pistons are readily available, so I'm just going to have the head redone, bore out the cylinders .010" over, install new pistons, rings, main and rod bearings, new gaskets, new timing chain and guides, and call it a day.

 

Let us know how it all works out. Interested in your progress.

 

If you have white smoke it could be a blowed head gasket too .

 

Head gasket was intact. It was definitely oil being burned through the rings.

I found some grayish paste on the entire bottom of the oil pan, about 1/8" thick, and it was also coated on the oil pickup screen and tube, which is consistent in color to the catalytic converter material, which I already hollowed out.

I found 20 over pistons, so I'm going that route. I'll post some pics when I get the block and head back from the machine shop.

 

I Finally got the engine back from the machine shop.

I had it bored out and honed. The head was checked for cracks, had it resurfaced and put new valve seals in it.
I bought new .020"-over pistons, new main and rod bearings (std size), new head gasket set.
I will start putting it back together tomorrow. I'll post some pics then.

 

What I still don't understand is how could the catalyst material get sucked back into the engine, if this engine does not have an EGR system. Once the exhaust leaves the block and goes through the cat, it does not get reintroduced into the engine.
Can anyone explain this?

 

Backpressure I believe.

 

From BITOG

The cat (converter) is right off the cylinder head almost, when you let off on the gas you get high vacuum in which some of the exhaust gasses go back into the engine, more typical on manual transmission cars because of the driving nature... The cat (converter) junk scores up the cylinder walls and can cause big time oil consumption.

 

It must have cost a fortune for the engine prep

 

fortune? not really. Machine shop bill was $368, all parts were about $350; I'm doing the labor myself.
The least expensive USED engine I found was about $1200 (with 90k miles) plus tax with only a 90 day guarantee. Who's to say the same problem has not already started with any used engine.

Rebuilding the original engine made the most sense to me and at a lower cost than a used one. This way I have the reassurance of doing it myself and making sure it's done right. I will practically end up with a "new" engine.

 

Has anyone reused their head bolts? The manual says to check the diameter of the shanks, if they are too thin they should be discarded. The way they are installed, is to stretch them.
I think I'll just buy a new set to be on the safe side.

I put the new bearings in last night. I'm working on the pistons and piston rings now.

 

Go with ARP studs-bolts , are you the one that want to have some Cosworth internals Nojodas !

 

ARP?

What are Cosworth internals?

 

Or factory OEMs if you need some . @ Nojodas .

 

Cosworth cams , pistons , crank , connecting rods , etc , it must not be you then , sorry about it , ARP bolts , studs , i ll give the links shortly '

Here s the link for Cosworth ; http://americas.cosworth.com/automotive/performance-aftermarket/

& for ARP : http://arp-bolts.com/

Top quality products .

Hope it will help you there . Cosworth s a bit overkill , if you have access to a machinist he can check the bolts , & / or nuts for you if they re still good , I mean if they re not too stretched , but almost no one check them .

 

Cosworth cams , pistons , crank , connecting rods , etc , it must not be you then , sorry about it , ARP bolts , studs , i ll give the links shortly '

Here s the link for Cosworth ; http://americas.cosworth.com/automotive/performance-aftermarket/

& for ARP : http://arp-bolts.com/

Top quality products .

I'm not building an urban street rod, I just want to get this car back on the road.

 

Sorry . I took you for someone else , lol

 

True , next year i ll buy another engine as a spare , as well as another tranny too . You re saving allot by doing it yourself , I taught you had it rebuilt .