#4 intake valve issue - 95 VX

[Darkelf]

Looking for advice/recommendations on an engine that creates white smoke on startup only.

Da parts:
'95 VX w/ 140k on stock D15Z1 engine/head

Da things I've done:
Valve lash adjustment (smoked prior to adjustment but worse after)
Leak down test
Thorough cleaning of all parts on intake side of head

I am confident of the valve adjustment and double checked them all- all are right in the middle of the range as per Helms

The leak-down test showed no major problems with(from R-L) #1cyl=25% ; #3 cyl=22% ; #4cyl= 20% ; #2cyl=25%(blowby out filler neck and dipstick on all cyl.)

Still had fairly large amounts of white smoke out exhaust on startup. So, Did the leak-down with the engine *cold* and the #4cyl shot up to 40% with blowby coming out the TB.

So, apparently, something is not quite right with the #4 intake valve. The good news is that when the engine is warm, it runs fine and doesn't produce any weird exhaust emissions. Otherwise seems to be in good shape.

My Questions:
1) How serious an issue is this?
2) What is likely wrong with the valve?
3) Could I tweak the valve lash more open or more closed and would that help create sort of a 'compromise adjustment' that could minimize the white cloud the car creates at startup?
4) What are my options?
5) Any other advice?

Thanks so much!!

[GasSavers_Erik]

A puff of white/blue smoke on startup by older vehicles is usually just slightly worn valve stem seals. You may also have a slight puff when you take off from a stop light as well.

The best case scenario is that it is a sticking valve and that it may clear up on its own or may just be an issue for the first few moments after startup. Perhaps oil deposits from the leaking valve stem seals have caked up on the stem and are preventing it from closing completely when it is cold.


You might rotate the valve a little (by turning the top of the valve spring assembly carefully- valves will bend if you get rough with them) and add air to the cylinder at TDC with a spark plug adapter and see if the hissing out the TB increases/decreases after rotating it a few degrees.

The only experience that I have with a bad intake valve was on a small block Chevy engine. The idle was erratic and unstable- when I tore it down, the valve guide was so worn out that the valve wasn't centered well enough as it closed to seal properly.

140K seems way too soon for valve guide problems.

The valve stem seals can be changed without pulling the head- you just need a special lever type spring compressor and use air pressure to keep the valves from falling into the engine when you remove the springs.

Maybe you can hold off until your next timing belt change is due and just pull the head then.

How much oil is it burning every 1000 miles?

[Darkelf]

Originally Posted by Erik

A puff of white/blue smoke on startup by older vehicles is usually just slightly worn valve stem seals. You may also have a slight puff when you take off from a stop light as well.

Sadly, this is quite the cloud and continues for several seconds then starts to die down till it's warmed up.

Originally Posted by Erik

How much oil is it burning every 1000 miles?

Truthfully, haven't driven that much yet but it doesn't seem to be burning any appreciable amounts.

Thanks for the tips, I'll give them a try and see if the problem improves.

[GasSavers_Erik]

Does it smell like smoke- or might it be steam (from a coolant leak into a cylinder)?

Perhaps if you disconnected one plug wire and then started it cold/repeat with a different plug wire after it cools off- and looked for the smoke- you could then determine if the smoke is originating from all of the cylinders or just one - if it is coming from just one cylinder, the smoke would not appear when that spark plug was disconnected.

If the valve stem seals are really bad, you should also get a big puff of smoke when you rev it after it has been idling for a few minutes.

[GasSavers_Erik]

Two more thoughts-

1. This is a manual trans right?

If it was an auto trans and if there was a vacuum hose going to a shift control valve low on the trans, you might check that vacuum hose for fluid inside to make sure the vacuum diaphragm was still OK. I had to replace one years ago on a car that was smoking horribly- it was sucking trans fluid through a broken vacuum diaphragm up through a vacuum line and burning it.

2. Brake fluid

Sucking in/burning brake fluid is also a possibility if the master cylinder is bad and is leaking brake fluid into the brake booster. Pull off the large brake booster vacuum hose that attaches to the intake manifold and make sure it isn't wet inside- and check to see if your master cylinder is low on fluid- most cars have a warning light

The more I think about it, the more I like the brake fluid idea- it very slowly leaks fluid into the booster for several hours and then sucks in/burns the whole gulp of it at cold startup. As soon as that big slug of brake fluid is burned, all is well- until it sits overnight and enough leaks/build up again.

[IndyFetch]

As with Erik, I am not entirely convinced the smoke is from oil. 9 times out of 10, the smoke color is as follows:

Blue: Oil
Black: Fuel
White: Coolant

If it was coolant, however, I could not explain why it would only smoke at startup.

[kamesama980]

brake fluid ingestion: you'd have to have a failed primary seal and cup AND a vacuum booster boot that failed on the MC side...possible but not likely. also the hose is usually not at the bottom of the booster where you'd suck up the fluid. are you losing any brake fluid? is the pedal super heavy to the point you almost can't stop the car? if no to either of those, this isn't the problem.

coolant: actually it'll smoke worst during startup if the HG is blown, cracked head, or cracked block. as the engine sits, coolant can seep in and build up so you get a hard start and big cloud on startup. running you don't get it leaking in as much so no smoke. this smoke will only last, at most, 20-30 seconds though (ask how I know :-p) if you pull the rad. cap while the engine's running you'll see it bubbling as combustion gasses leak out the same crack/leak into the cooling system.

valve stem seals are probably bad. 140k isn't too early for that by any stretch. that would cause smoke on startup and after idling for a while. the guide could be bad if something got through the filter and past the seal and started grinding away. guides won't affect leakdown though. valve seats will but that won't get worse from valve lash adjustment.

going along with that... if you're getting leakdown air out the TB after doing a valve adjustment, you did the adjustment wrong and the valve is being held open. run the engine like this and you'll ruin the seat and burn the valve pretty quick.

a leak down test with air noticeably coming out anything is a bad one. did you calibrate the gauge right? coming out the oil cap and dipstick tube is 100% rings, perfectly reasonable in an engine with 140k. expected unless it's taken care of just right. during cold start, everythings cold and fits poorly so you get more oil past the rings and blowby in the other direction. As the engine heats up and everything expands, it seals better so smoke dies down.

[GasSavers_bobski]

Originally Posted by kamesama980

[...] if you pull the rad. cap while the engine's running [...]

Erm... Don't do that. Seriously. That is, unless you enjoy trips to the emergency room with burns over large areas of your body. It's safe to take the radiator cap off when the engine is cool, and you can then safely start it with the cap off, but don't take the cap off when the engine has been running for more than a minute or so.

[Darkelf]

I appreciate the concern and warning... I fortunately already knew to be careful of opening hot radiator caps from a friends' carelessness in my youth.

So, I've tried the things suggested [pulling one plug wire, re-checking brakes (just did a brake job), checking for bubbling coolant] and it seems to be leaning towards worn valve seals.

Pulling the #4 plug wire *reduced* the white cloud -which, by the way, seems to have a bit of a gas smell but not real strong... running rich?- but did not eliminate it. Blipping the throttle did produce another small cloud.

Brakes work well and haven't lost fluid -firm, appropriate pedal feel.

No bubbling or gurgling of the coolant with the cap off. Can clearly see the coolant flow as I blip the throttle and no bubbles during startup or as the engine warmed (tho, didn't wait for normal op temp).

So, good news and bad, I suppose.


My next question then is:
Is this considered a serious engine issue? I would like to sell her but neither want to be disingenuous about trying to "do a quick fix" nor short myself by taking a huge loss (I need the $!)

It runs fine (except for a curious # 48 CEL on a known-working O2 sensor that is on another thread).

Thoughts?

Thanks for all the inputs thus far!

[kamesama980]

Originally Posted by bobski

Erm... Don't do that. Seriously. That is, unless you enjoy trips to the emergency room with burns over large areas of your body. It's safe to take the radiator cap off when the engine is cool, and you can then safely start it with the cap off, but don't take the cap off when the engine has been running for more than a minute or so.

... sorry, forgot to add a note for the lowest common denominator: if it's hot to the touch it's hot inside too. 'scuse me!

I'll open them till the upper hose, rad cap, or upper tank on the radiator is hot (any one of them i mean) but slowly with rags or something to deflect/absorb the hot coolant. heck I've opened them while overheating... but I use something to very surely protect myself

suggestions of what to do with the car: valve seals shouldn't be too hard to do. I've only opened 1 or 2 honda heads but if you can get a spring compresser on the valve springs, doing the stem seals is a piece of cake. also, recheck the valve clearances and double check that you had the engine at the right place when you did the leakdown test. If we were closer I'd offer my help fixing it.