Engine health
 

As some of you know, I own a 96. The car currently has 66,000 miles and when I bought it about 2 years ago it had 55,000 miles.

In the time I've owned the car and before I turboed the car I had 2 blown headgaskets due to the infamous Mazda "cooling route". The second time it happened I decided to use that time to have a slight porting of the head done. Really not much was done; just that and changing the valve seals.

The car has been running like a dream but I've had 3 instances when I've noticed some white smoke coming out of the tailpipe for about 30 seconds; checked my gauges and nothing was out of the ordinary. The last time, it happened while my car was idling while I waited for my wife to do a short errand. I couldn't have been idling for more than 3 minutes when it happened. I turned the engine off; turned it back on and the smoke was gone.

I must also note that I've been using about 1 quart of oil every 1,000 miles. I was previously using Mobil 1 10w 30 and changed it to 5w 50 last time I changed the oil. This had an immediate and noticeable effect on the oil pressure which went from less than 25 to over 30 on the gauge.

A few days later; as I started the car in the morning I noticed that when I did so, the car would start misfiring (like it was running on 3 cylinders) and a minute later (after stepping on the throttle and slightly revving the car) it would begin to work properly again. I decided then to take it to the shop and check the spark plugs. While there, I asked to have a compression and a leakdown test done. Even though they had the leakdown test kit, they couldn't do that test because they don't have an air compressor. They did perform the compression test and these were the results:

Cylinder 1: 200
Cylinder 2: 175
Cylinder 3: 200
Cylinder 4: 200

So, I took that opportunity to change the spark plugs (even though these had only been in the car for 3 months) and found some carbon buildup in all but #2 was wet while the others were dry. BTW, I'm running #7 NGKs.

I spent quite sometime yesterday afternoon here, doing some search on "compression test" and leakdown test" and I have a question:

I read in one of the previous threads that the problem could be related to valve seals and not to the pistons per se. I'm inclined to think that is the case for me. If so, what should I do?

Thanks

If the valve seals are going, you'll tend to get a bit of smoke right when you first start the engine, but not thereafter. The reason for this is that a smallish quantity of oil can find its way down the seals and guides and into the chamber while the engine is stopped, but under all but the most horrid, valve-bending conditions the rate of flow of said oil will be miniscule. While the engine is running, the nearly immeasurable amount of oil that can travel this path in the time of one cycle will be quickly burned off without there being time for enough of it to accumulate to make any noticeable smoke.

Thank you. That's bad news.

I still need to get some info on what should be my next step.

I guess I have do the leakdown test and proceed from there.

I got another stupid question: the symptoms you mention are the ones I notice in the morning when I turn on my car for the first time. In fact, there's a black stain on the wall just behind my car's exhaust at my parking spot. But in that case, it's black smoke, while the instance I mentioned with white smoke happened after I had been running errands for more than 30 minutes and in the middle of the day. What is white smoke related to?

I think the black stain is the rich cold start - that's not uncommon.

Having you're low cylinder clean is usually a sign of coolant leak, not oil. Generally speaking, generous smoke on a cold start and then clearing up is usually rings if it's oil (blue) smoke and a head gasket if it's coolant (white smoke). But the latter is more common on mls gaskets than composite.

Get your shop to put a little bit of oil in your low cylinder and see if the compression comes up. If it does, it's the rings. And make sure they do the compression test on a warm engine.

As usual; thanks for your input Rob. I appreciate it. :bigtu:

FWIW, they did the test after I had been at the shop for about 15 minutes.

I presume you're talking about doing a "wet" compression check besides the "dry" one I had done yesterday; or I'm I misunderstanding you?

Your answer provokes another stupid question. If it's a ring; does it mean I should start thinking about totally rebuilding my engine?

If you don't have emmisions, I would drive it untill it smoked bad. Have you checked your water? Check and see if it is low. Or if your oil is starting to get a coffee with milk color.
Isn't 175 still a good number?
Although, 1quart per 1000 is a lot. Are you driving it hard? Mine does that when I race around alot.

No emissions here ;)

I don't drive it hard; I'm an old fart plus I'm a pussy! :giggle:

I do think that I must also have some oil leak because I find oil consumption too high.

BTW, I've checked the oil and there's no mix with water.

I was thinking about a product I read that Pat mentioned in another thread: "Engine Restorer"; does anyone know how and if it would work?

I suspect Rob is dead on and I've got a problem with the ring on piston 2.

yes "wet"

I wouldn't put anything in the oil. I'm a skeptic when it comes to the miracle cures. I mean, how does it fix metal yet safely pass through the oil filter? And that oil goes through your turbo.

I was reading this thinking to myself "I already told him how to fix this" and then saw this! I swear by the stuff. 99.999% of all the "miracle in a bottle" stuff is crap. But this stuff WORKS. Give it a try. Run it for say 5K miles and then have the compression test done again. Bet it goes up some.

"engine restore" works, but only a temp fix. I would put it in a street car over and over for years...but never in a track car.

I'm stuck at home (caught an unexpected cold yesterday afternoon) so I decided to search the internet for "Engine Restore". I have about 7 days before I can get my hands on that product (I have to buy it through Amazon and it's going to take more than 1 week to get it here) so I'll keep on researching and try to do the "wet" compression test and the leakdown test. If I can get my hands on an air compressor, I'll post results.

I will delay the final decision until I can do both tests and get additional suggestions but; my current plans don't include rebuilding my engine until the middle of next year. If that stuff can get me to that time, I'll try it.


As I mentioned above; I'm buying it and I will see how the tests come out.

BTW, I've been following your progress. I'm impressed! :bowdown:

Meh. When valve stem seals leak, it's pretty easy to diagnose. When at idle, there is vacuum in the intake manifold. Well, that puts vacuum on one side of the valve stem seal. And of course there's atmospheric pressure on the other side. And oil too. So oil is literally "sucked" through the stem. Of course oil is heavy and doesn't vaporize readily like gasoline would. So it leaks in the port and literally "sits and acuumulates". Then when you start driving, the velocity of the air increases and pushes the oil all out.

IE-old ford sitting at a red light for 5 minutes and blows out a cloud of smoke when they take off, but it then clears up and seems to run perfect.

If you want to diagnose the problem, do a leakdown test. Find a shop that can do one.

Engine restorer will cause seals to swell slightly, making them seal again. Also makes rings seal too. I went from 140 PSI across all 4 cylinders in my 86' trooper to 185 on all 4 after putting 5K miles with engine restorer. Could tell 10 other success stories.

I'm back with some additional stupid questions.

I was informed by my forwarder that the "engine restore" can is here so I'll pick it up today.

Before proceeding with it, I wanted to ask some questions;

My car has begun to smoke (white smoke) much more frequently in these last 2 weeks. I did notice that this didn't begin to happen until I changed motor oil grades (went from 10w 30 to 5w 50) about 1 month ago.

As soon as I changed the oil I saw much higher oil pressure in my gauge and this was also the first time I began to notice occasional puffs of smoke. So I have to ask:

1) should I change my oil before putting in the Engine Restore?
2) Should I go back to the oil grade I was previously using?

Thanks

I'd run a 10W-30. I run 10W-30 Full synthetic mobile 1 in my car and it does good. Change it every 15-17K miles whether it needs it or not.

If your engine didn't hold good oil pressure at idle when warmed up (less than say 10), I'd run a 10W-40, else I'd run a 10W-30. You can put the engine restorer in with an oil change or just dump it in.

Thanks man!

Rafa,
I'm with Pat on the valve stem seal possibility.
Easy test:
Warm up the car, then let it idle for 10 minutes. Then rev the engine hard a couple of times. If you see a cloud of very light blue (almost white sometimes) smoke coming from the exhaust, then it might be a valve stem seal. As Pat indicated, the very high vacuum condition of idle sucks oil down the stems of the valves and onto the intake port end of the valve. When you open the throttle and rev it up, it sucks that oil off of the valve and into the combustion chamber and it burns to make the smoke.

When other people talk about "white smoke," be very careful not to be misled. It is not white smoke that they are talking about. It is steam. They should not call it smoke. It comes from the coolant/water being super heated in the engine. If steam comes out of your exhaust it is easy to tell the differece from smoke because in Santo Domingo it is warm enough for the steam to disappear within 4 or 5 feet of your car. Smoke will not.

One more thing. On some turbos an air inlet restriction (air filter clogged or too small) can create enough vacuum to suck a little oil from the center section of the turbo, past the shaft seal, and out towards the intercooler and engine. If this happens, you can see pale blue smoke under throttle.

But I'm still thinking valve stem seals. A good shop can change them with the head still on the car. It takes the right tools.;)

I hear you but; I've got a few observations:

1) It's definitely white (oil) smoke. It smells like burnt oil.
2) If it were the valves; why would I see a much lower reading on cylinder 2 when I do the compression test?
3) There's no pattern to when it happens. It only does so while my car is idling after some time driving it but it doesn't happen every time I stop.
4) Today, it happened 4 times. That hadn't occurred before.

For some piece of mind, I'll follow your advice and change the valve stem seals before doing anything else.

One final thing; I strongly suspect it has something to do with the change in oil viscosity. As I stated before, I didn't see this happening when I was using 10w 30. It began to happen when I went to 5w 50 oil.

I was noticing that my oil consumption was pretty high (around 1/4 per 1,000 miles). And BTW, I religiously change my oil every 3,000 miles.

I'm inclined to use the engine restorer just to gain some additional time. I'm about to install a new LSD diff and the car is going to go into the paintshop on the 6th to get the new rear bumper installed and to fix some small paint details.

I don't want to have to build the engine for at least 4 or 5 months.

Thanks for the help. I really appreciate it. :bigtu:

Your compression test is not that bad, only about 12% variance from the other cylinders. I would try going back to a 10w30 before trying the Restore stuff. And if you do try the Restore additive, keep in mind that's about half a quart less oil you will be using.

Rafa, your compression results are better than mine. But I'm boosting anyways.

FWIW, compression test doesn't mean anything compared to a leakdown test. Seriously. You could have a bit of carbon buildup on the other 3 cylinders and that is causing them to read higher, even though all the cylinders are worn the same. Just an example. If there is a problem, a leakdown test will pinpoint it. I'd keep looking and find someone that can do it. Do you happen to own an air compressor? You can buy the leakdown tester pretty cheap, and doing the test is as easy as changing plugs.

Rafa,
Since it wasn't too long ago that you changed the seals and it appears to only be oil fouling the number 2 spark plug, I would suspect that the seal might not be bad due to age (drying out and shrinking/cracking), but due to being cut during installation or being slightly out of position. The restorer would not help these conditions.

I would check on removal and replacement of just the two seals on the two intake valves on the number two cylinder.

Your compression is within tolerances. So you probably don't have a cracked piston ring.

Be careful boosting in this condition because excess oil in the combustion chamber will cause detonation...

Lunch today at Arco Iris: Bistec salteado, arroz amarillo, yucca, garbanzos, plantanos, cafe Cubano. :)