Blowin' Smoke

Matthew68

Well-known member
Hi All,

I have a 1968 Mustang Coupe with the 200ci. Pretty much stock engine other than a Pertronix and Coil, no other upgrade to any engine parts. The car is new to me, bought from a neighbor. They have records going back to the early 1980's, albeit sometimes they are just more of what was done rather than exact parts, etc.

Anyways, I'm having two main causes for concern:
1. Upon cold start, I'm getting some blue-ish smoke from the exhaust. It definitely has a "scent" to it like it's burning a little oil. The smoke seems to dissipate after getting warm, but there is still a smell.
2. Low oil pressure when braking primarily.

A few things to note - I'm using the standard "dummy" gauge for oil pressure now. I realize I need to put a mechanical gauge on there, and I've already ordered it. The dummy gauge goes almost to the low point until acceleration begins, then creeps back up. On straight roads with no stop and go, the dummy gauge goes back to the middle until braking occurs.

I completed a compression test today - dry test only, car was warmed 10 mins or so before completing. Compression seemed good on all cylinders:
Cyl 1 - 155
Cyl 2 - 170
Cyl 3 - 165
Cyl 4 - 165
Cyl 5 - 170
Cyl 6 - 170

Each spark plug had oil on it. I took photos, I'm hoping they come through.

Thoughts? Not sure what would also be causing the low oil pressure upon braking.

Cheers,
M


PS - I am literally brand new to the backyard mechanic thing. Extra patience and guidance is appreciated - you've guys have been a world of help to others. TIA!

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Hi, yes it looks like you are burning a little oil. That is probably valve stem seals. I probably wouldn't worry about that unless you really pump the blue smoke out of the oil filler neck. Your compression #s look good.
Low oil pressure usually means worn bearings, but could be something you can live with.
If you don't know what oil is in there I would try Castrol GTX 10-40 or 20-50. Lucas oil treatment is also very heavy and could keep the pressure higher at idle. I got many years out of an engine that would have very low pressure at idle by using 20-50 oil in it. Try the simple things first and get the Falcon Performance Handbook to get the most out of your Ford 6. Make sure the brakes are all OK and be safe and enjoy your car. Good luck
 
Thanks, B RON CO. I should also mention the smoke is not a lot, but noticeable enough especially with the smell. The car has 155k on it, with the head rebuilt in 1983 around 109k. I don't know what all was done unfortunately.

As for oil, it's been 10-30 high mileage. I'm changing the oil to 10-40 this weekned.

With worn bearings, wouldn't I notice low oil pressure all the time? It seems to be just on braking.

Cheers,
M
 
Howdy M:

Your plan on the oil pressure gauge is right on. 1st step- get quality information.

On the oil pressure issue start by assessing with a fresh set of spark plugs gapped at .040"'. Your plugs in the pictures are beyond resurrection. Switching to straight weight oil of #30 or 20/40 may be worth a try. I'd be willing to bet that your problems are the oil pressure gauge you're using and your valve stem seals.

Once you get new plugs installed do a driving test with the engine completely warmed up and the choke open. Try decelerating from 50 mph, with the engine in gear and then accelerating while watching for smoke from the exhaust. If you get a blue puff that's a good indication your valve stem seals are not doing their job. Also watch the exhaust for smoke on start up.

Check you plugs now, after the drive.

Also given the results of your compression test your rings and valves seem to be reasonably good.

If you're still in doubt pull the valve cover and visually inspect the valve stem seals.

Good Luck. Keep us posted.

Adios, David
 
Thanks, David. I put a new set of Autolite Coppers in after I did the compression test. I gapped them at .035. Should I pull them an switch to .040? Or should I perform your recommended driving test as I have them now?

Also, should I perform the test before I change the oil to the 10-40 or do it at the current 10-30?

Sorry for so many questions....

Cheers,
M

Edit: I do in fact get some blue smoke on startup - I can confirm that today. My driveway just got sealcoated so the test drive will have to wait a day or two until it's fully dry.
 
That 68 Mustang is a good one to have and you are at the best site for it. If you are having low oil pressure it might help to go to thicker oil as stated like 20-50 not 10-40. Or as David said straight 30 weight. Definitely get the Falcon Performance Handbook it is a solid investment.
 
X3 I agree that you probably will need to replace the valve stem seals, it's a job that can be done fairly easy with the head still installed. As to the drop in oil pressure when braking also check the condition of your oil pan under the car. If the oil pans sump has been bent in, you may not have your full oil capacity and the oil pan will need to be straightened or replaced. If the oil pan is not caved in on the bottom then you may need to install some baffles inside the oil pan to help keep the oil in the bottom sump during braking and acceleration. Good luck :nod:
 
Howdy Back M and All:

In this order;
1. Do the deceleration/accelerate test first. The deceleration period is high engine vacuum and will likely pull oil into the combustion chamber if the valve stem seals are bad. Then, when you accelerate again your engine will burn the oil and you'll see smoke out your exhaust. If bad valve guide seals are the problem, check back to explore your options.
2. Get a good quality, accurate oil pressure gauge and see how it reads. If you're still seeing the odd fluctuation in pressure, that's the time to look farther into it.
3. IF the new pressure gauge solves the problem- good. You can change to a straight weight #30 oil next time you need to change oil and filter. #30 for summer driving. 10/30 for winter driving.
4. The new plugs are great. Next time you pull them to clean re-gap to .040". You might as well be taking advantage of the better ignition and hotter spark from the Ignitor and coil.

You didn't mention what you have your initial advance set to. If you haven't yet, set the initial advance to 5 degrees more then stock spec call for. If this is a manual trans car, set at 10 degrees initial. 16 btw for an auto trans engine.

We'll be waiting anxiously for your result. Don't forget to share them here.

Adios, David
 
Thanks David and All.

I will do the drive tomorrow more than likely. Going to be in the 90s today here in Ohio and drop 20 degrees tomorrow. With no AC, I'd prefer to be a little more comfortable! I'll report back with pictures of the plugs. When I pull them, I will also regap to .040.

As for the initial advance, here is where I will show my beginner-ness. I've never timed a car, and never known how to. I'll refer to the Chilton's manual to see if it tells me how until Matt is back in stock with the Falcon manual. I don't have a timing light or any other tools to help me. I assume I need to take off the radiator fan for this?

I'll report more on the oil pressure once I get the mechanical gauge on there. I'll post some pictures of the pan this weekend when I do the oil change.

David - when would I switch from 30 to 10-30 and reverse? I'm in Ohio where we get all 4 seasons. Didn't want to do it too early or too late for that matter.

Thanks for all your help so far, all. Hope you're not sick of me yet I'll be around for a while!

Cheers,
M
 
Matthew68":2hn3b2zl said:
"... Hope you're not sick of me yet I'll be around for a while!
Cheers,
M"
We all gotta show up.
It enriches us ALL.

On the oil (same climate here) the change happens along w/ambient temps. The thinner oil will flow easier in the cold, so like farmin we change w/the seasons (the real on the ground happenin, not a calendar). The higher number, thicker, when we wanna protect during the hot weather…

Look 4 ya on the rebound!
 
Howdy Back M:

I usually switch when the overnight lows start getting into the 20 degree range. And back to summer weight oil when day time highs get back into the 70s. Once you solve your pressure dip you may want to go back to a multi weight oil full time. Many do.

On the initial advance setting, No, you will not need to remove your fan. Start thinking about investing in a good quality timing light- usually about $25, but I haven't bought one in quite awhile so ???

Start by finding the timing mark on your engines crank pulley. The mark is a nick on the rim of the pulley. The pulley is usually pretty grungy so take some rags and cleaner spray with you when you go under there. Once the mark is clean, highlight it with white chalk or paint so it will be visible for a while. Now do the same for the timing tap on the top- toward the left, in front of the distributor. The timing tab is a flat piece with numbers stamped in to it and "Saw like" teeth on the front. Clean it thoroughly.

Now you are ready for the timing light. Your new timing light will have directions included. Read them thoroughly. Also there are many "How To" clips on the web. Once you've schooled yourself, if you still have questions, ask away.

Another issue on old engines is the timing mark on the outer ring of the pulley can slip and give a false reading. You can easily check that by rotating the engine until the timing mark lines up with the "0"on the timing tab. IT is easier to get the timing mark and "0" lined up if the spark plugs are out.

Now look into the #1 spark plug hole to see the top of the #1 piston. That piston should be at the very top when the timing mark is at "0". IF it is not, well, lets talk about that later. After the timing lesson is over.

That and the Chilton's should get you started. Take your time. Keep it coming.

Adios, David
 
Thanks for the info on the oil, David. I failed to mention also it's an automatic transmission, FWIW.

I'll be taking the car out for the test later today or tomorrow but wanted to make sure I fully understood what you want me to do. If I understand you, it's the following:

1. Start the car, let it warm up. (I've never had to close the choke to start the engine luckily)
2. Take it out on a road up to 50 MPH
3. Foot off the gas to slow the car naturally, to what MPH?
4. Step on the gas and watch for blue smoke
5. Return home, pull the plugs and post pictures
6. Wait for wisdom from FordSix members

If I misinterpreted any of that, please correct me. I want to make sure I'm accurately testing for the valve stem seals and not doing the test wrong. I'll await confirmation - thanks!
 
I didn't get it out for a test drive yet, driveway is still drying from sealing. I did for good measure change out the PCV valve and grommet, I don't think they've ever been changed as the grommet was hard as a rock. More blue smoke upon startup and any time I pressed the accelerator.

I checked for timing marks, and it looks like it's a little rusty. Any tricks to remove it? I was thinking sand paper but didn't want to damage anything. I attached photos.

Cheers,
M

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I'd use some kinda rust buster, penetrating fluid anda wire brush. Wouldn't worry bout hittin the shive w/my errant strokes cuz its kinda rusty too and may not treat a new belt very nice...
 
Howdy Back M:

1. Start the car, let it warm up. (I've never had to close the choke to start the engine luckily)
Yes, but warm it up by driving it.
2. Take it out on a road up to 50 MPH
Yes, in drive.
3. Foot off the gas to slow the car naturally, to what MPH?
Yes, Simply take your foot off of the gas pedal, leave the car in gear. Decelerate to 35 or 40 MPH.
4. Step on the gas and watch for blue smoke
Yes, step on the gas and accelerate briskly back to 50, while watching behind you for the blue cloud. Be careful while watching the review mirror.

Are you saying that the timing tab is rusty? If so, no worry. The numbers stamped into it.

Did you find and clean the timing nick on the damper wheel yet?

Adios, David
 
You can brush the tab to reveal the numbers and swipe them with a dab of white paint. If/When you find the flywheel notch, put a dab of white paint on it too.

HOWEVER, the outer ring on the flywheel may have slipped on the rubber bushing, so you need to find top dead center. When you do that, THEN put the dab of paint on the flywheel at the notch on the tab.
 
Hi All,

Back from the test drive. No huge cloud of blue smoke, but there was definitely some. A little more than startup. About the same amount as if I were to pump the accelerator in the driveway parked. Hard to tell perfectly from the rear view, though. I pulled the plugs and took pictures below. Thoughts?

I also regapped to .040.

I will work on uncovering the timing marks. Had to go get some degreaser and wire brush. I'll report back later on that.

Cheers,
M

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Chad, your suggestion worked. I got a metal wire brush and can read the nicks much better. Not perfect, but can make them out. Thanks!

I also found nick on the pulley. A friend has a timing light and will bring it by in the next few days to use. More to come on that end. Thanks for all your help so far, much appreciated!
 
Howdy:

Be sure to note the initial timing before you change anything. I seem to recall that this is an auto trans car. Specs for manual trans engines call for 5 degrees tdc. With an auto trans stock is 12 degrees BTC. For performance and best MPG set at 5 degrees over stock specs and assess.

Any progress on the oil pressure gauge?

The new plugs look good. But I'm still betting your valve stem seals are the culpret.

Adios, David
 
Hi David,

No, not just yet. I'm searching around for a T fitting so I can use the old gauge (with a new sender of course) and also attach the mechanical gauge. The oil pressure gauge won't be here until mid week next week, which I will be out of town for. I'm hoping to have everything come in next week and be able to put it on next weekend. If I'm silent for a while, that will be the reason.

Rest assured, I'll be back.

Will the timing light tell me what TDC and initial timing is? Or will I need to find that manually? Thanks for the insight.

Cheers,
M
 
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