Blue smoke out the tail pipe sometimes

Timothyeg · Sep 13, 2020

Hi everyone,I have a 2002 mustang gt that i bought 2 months ago and it only has 74,000 miles on it. It's in great shape cosmetically! I does run really good also except sometimes when I start it up it blows out some blue smoke.When I first bought it it didn't seem to do it unless I just never noticed.Anyway it seems to be doing it more often and I am not quite sure what it is.There is maybe a little powerless and it seems to havI love e a shaky idle.I recently had the plugs changed cleaned the maf and tb, and iac.I was thinking maybe valve seals ,not sure?If some oul is getting into the cylinders I believe that could cause a shaky idle.I love mustangs and have money into this one and hope it isn't a huge repair.I really need some opinions on what people think is going on.It doesn't just blow blue smoke on a cold start.It does it sporadically, here and there not all the time .Thanks for any help.

Timothyeg · Sep 13, 2020

Timothyeg said:
Hi everyone,I have a 2002 mustang gt that i bought 2 months ago and it only has 74,000 miles on it. It's in great shape cosmetically! I does run really good also except sometimes when I start it up it blows out some blue smoke.When I first bought it it didn't seem to do it unless I just never noticed.Anyway it seems to be doing it more often and I am not quite sure what it is.There is maybe a little powerless and it seems to havI love e a shaky idle.I recently had the plugs changed cleaned the maf and tb, and iac.I was thinking maybe valve seals ,not sure?If some oul is getting into the cylinders I believe that could cause a shaky idle.I love mustangs and have money into this one and hope it isn't a huge repair.I really need some opinions on what people think is going on.It doesn't just blow blue smoke on a cold start.It does it sporadically, here and there not all the time .Thanks for any help.

I forgot to mention there isn't a lot of blue smoke and once I push the gas down from this initial start up I could rev it a little bit afterwards and usually don't get smoke afterwards.I was wondering could a bad intake manifold gasket cause this blue smoke? Maybe it's not the valve seals.Any thoughts.I am a die hard mustang enthusiast and I don't want to shop around for another one! Any help would be enormously appreciated!

79PaceKar · Sep 13, 2020

Hello: I had this problem with an 83 Escort GT. Took it to the Ford dealer for advise as I was about to be stationed in England and wanted to take it with me. I was asked how much oil I used in 3,000 miles. I said not much, maybe half a quart. They said it was a valve guide. If the valve was open when the engine was off, the oil would run down. If closed, not so much. Said if it gets bad, have the valves done. If not much, keep and eye on it and don't worry. About 30,000 mile later I had the heads rebuilt. Not to bad until it really started to burn oil. Had the heads rebuilt while in England. The Escort LOVED being driven in the small windy ( not straight roads) ( I know it looks like the wind blowing) back roads. Never did catch up with Minis ......Larry

Deleted member 38176 · Sep 13, 2020

Had the same problem. Replaced valve seals and guides, problem gone

Timothyeg · Sep 13, 2020

Nightfire said:
Had the same problem. Replaced valve seals and guides, problem gone

Does this sound like valve seals for sure?I hope not.Could a bad intake manifold gasket do the same thing with blowing smoke if the gasket isn't sealed properly?How expensive of a job is it?How much labor do you think?

Timothyeg · Sep 14, 2020

Timothyeg said:
Does this sound like valve seals for sure?I hope not.Could a bad intake manifold gasket do the same thing with blowing smoke if the gasket isn't sealed properly?How expensive of a job is it?How much labor do you think?

Also tested negative for head gasket problem.

Deleted member 38176 · Sep 15, 2020

Blue smoke is oil being burnt. As your car sits (overnight for example), oil is slowly leaking oil into the the chambers, hence the cloud at startup.

Timothyeg · Sep 17, 2020

Nightfire said:
Blue smoke is oil being burnt. As your car sits (overnight for example), oil is slowly leaking oil into the the chambers, hence the cloud at startup.

Does this sound like valve seals?How long does it take to replace them? Car only has 74,000 miles on it ,but the guy a got it from hardly drove it.He put 5,000 miles on it in 7 years which isn't much.I know you can have problems if you let cars sit.J have hammered on it a few times but have taken it easy on it since I seen the blue smoke.Hopefully I didn't do something to it from rodding on it?

Timothyeg · Sep 17, 2020

These are the pics of the stang. IT has air brushed flames on both doors

Timothyeg · Sep 17, 2020

Can't send all at once

7991LXnSHO · Sep 17, 2020

It sounds like valve stem or guide wear. Bad seals can allow extra oil to get to that area, and new ones might help disguise the problem. But with the mileage and age of the car, poor engine maintenance is more likely than age cooled seals.

Another time worn guides will smoke is when you are driving and go from an open throttle to closed. The snap rise in vacuum will suck some oil past the intake valves. This usually takes someone watching in the car behind until it gets really bad.

Timothyeg · Sep 17, 2020

Thanks for the info.If this is the case is it cheaper to put in a whole new engine? Who knows what else will go wrong .I do notice some lifter noise.Not a lot but it seems a little louder after I get on it some.I get home get out of the car and leave it running and it seems a little louder than when I left the house.It ends up quieting down .next day I get in it and it is pretty quiet again.Lifters aren't really that loud.some lifter noise is acceptable I guess.

7991LXnSHO · Sep 17, 2020

The jump from a 75k engine with a bit of start up blue smoke to a replacement engine is a big one.
A cylinder leak down test, compression test, and an actual oil pressure gauge reading (warm at idle and at higher RPMs) are ones that will help a lot in answering if more than a valve job is needed.

Timothyeg · Sep 17, 2020

Oil pressure seems right where it should be on the gauges when warmed up.Like I said I do have a little lifter noise.sometimes it's quieter and sometimes it's a little louder. You can hear it though.It does seem to run good but does have a shaky idle.I read that this shaky idle can come from oil leaking into the chambers although I'm not quite sure. It's hard to really predict which way this engine is going to go.

7991LXnSHO · Sep 17, 2020

I tried to specify a non dash mechanical gauge so you could see the actual numbers and an accurate reading. Lifter noise could be from low pressure or a lifter that would be easy to replace with the heads off.
Here is a couple of videos on what you need to do for a compression. Dave is a Corvair guru, but the tests are the same (Except for cooling) and he’s a hoot. Other videos might have cameos from Garage Chicken.

The compression test will tell if the engine is holding air at the right time. He also mentions reading the plugs, which is a great idea. You may have one or all of the spark plugs that show signs of oil burning.

View: https://youtu.be/8yBa-MwJQdY

The leak down test will tell you which way the compression is going if the compression is low.

View: https://youtu.be/jbg29iB4lZk

Deleted member 38176 · Sep 17, 2020

7991LXnSHO said:
The jump from a 75k engine with a bit of start up blue smoke to a replacement engine is a big one.
A cylinder leak down test, compression test, and an actual oil pressure gauge reading (warm at idle and at higher RPMs) are ones that will help a lot in answering if more than a valve job is needed.

Dont waste your time with this guy. A valve job isnt needed. Just need to replace the seals and/or guides. This clown has never owned a mod motor

stormsedge · Sep 18, 2020

How much oil is the motor using/how much are you adding?

7991LXnSHO · Sep 18, 2020

Nightfire said:
Dont waste your time with this guy. A valve job isnt needed. Just need to replace the seals and/or guides. This clown has never owned a mod motor

Excuse me, who are you calling a clown? I’ve been driving a 2v 4.6 for about 12 years and plan on hitting 200k miles before eventually selling it.

If you are referring to Dave’s how to videos, replacing valve guides without checking for proper fit to the valve stems is expensive hack job work that can easily lead to continued leaks or a stuck valve. And not making sure they seal to the seat well after replacing the guides is a waste of money.

If it passes the tests, trying new seals is a reasonable step.

Adizzle843 · Sep 19, 2020

Here is the invoice from the local machine shop. I bought the head rebuild kit from MMR. This is a recent invoice, so labor should be comparable.

Blue smoke out the tail pipe sometimes

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