Tech Articles

Ask Away! with Jeff Smith: Diagnosing Ticking Noises and White Smoke in a Supercharged ’93 Ford Mustang GT

 
silver ford mustang 1993 gt supercharged

(Image/StangNet.com – Josh1892)

I’ve been looking online for help to figure out what is happening to my car and I thought your expertise may help.

I have a supercharged ‘93 Mustang GT with a cam and aluminum heads. I noticed a slight ticking noise the other day when parked near another car. It’s not bad, but speeds up when I give it gas. I also noticed it puts out a little white smoke on startup after the car has sat for a little while. The noise also seems to get a little louder when the engine warms up. No notice of power loss or anything else, but with it being my daily driver for the next few months, it’s got me worried. I’ve had the car for almost 20 years and have a lot done to it. I would hate to have something going on in the motor.

If I could get your opinion that would be great. I will be headed overseas this winter and need to know if I should save for some motor work when I get back. — M.C. 

Jeff Smith: It’s difficult to diagnose a situation like this without hearing the noise, but I will hazard a guess that it could be one of a few things, starting with either a lifter or an exhaust leak. Both are relatively common.

Does the car have headers?

It’s not unusual for header gaskets to leak slightly and get louder once the engine is warmed up and the header expands. You can do some simple diagnostic work to locate the noise.

An exhaust leak can also be located by waving your hand above the header flange. If it leaks, you might be able to feel a small puff of air from the exhaust pressure pulse. We shouldn’t have to tell you to NOT touch the header. Often, simply tightening the header bolts will cure the problem.

If it’s lifter noise, sometimes a tiny piece of dirt can get lodged inside the lifter body above the internal steel check ball in the lifter. This allows the lifter to “bleed down,” and causes the lifter to tick. Sometimes just changing oil or adding a quart of automatic transmission fluid (ATF) will help. ATF uses high detergent concentrations and can sometimes dislodge the debris.

This works better with engines that haven’t been cared for, and have a sludge problem—which is unlikely to be your problem.

It’s nearly impossible to find and replace the one lifter that is ticking, and it’s expensive because the top engine has to come apart to even get to the lifters.

Another possibility is a potentially failing pushrod or rocker arm, which should be easier to identify.

You can start the investigation by placing one end of a long screwdriver on a valve cover and the plastic handle end directly on one ear. You’ll be shocked at all the noise that you hear. Move the screwdriver around the engine to see if you can locate where the ticking sound is located front to rear.

NOTE: Be careful not to wear any loose clothing that can droop down and get caught by the spinning fan or accessory drive. That’s a good way to really hurt yourself so please be careful when attempting this bit of diagnostics.

If you locate a louder noise toward one side of the engine, it will indicate an area for you to check when you pull the valve cover. This is an old-timer auto mechanic trick that still works. Just be really careful when doing this, please.

As for the smoke on startup—that often is a clue that oil has leaked past the intake or exhaust valve guide seal and entered the cylinder.

On startup, that oil is quickly burned. Has your motor oil usage increased? This is another clue that the valve guide seals are bad on the intake side as under deceleration high engine vacuum will pull oil past the seals. Look for oil on the threads of the spark plugs. If only two or three plugs have oil on them, those are probably the offending cylinders. If all the spark plugs exhibit oil, it’s possible the seals are worn and need to be replaced.

You didn’t mention if the car has an automatic transmission.

Another potential problem involves older automatics that use a vacuum modulator valve. This valve is hooked directly to engine manifold vacuum. If the rubber diaphragm inside the valve splits, it will suck ATF from the valve directly into the engine. This is not your problem since the smoke goes away after you start the engine, but ATF tends to burn with a white color while engine oil is more bluish.

Hope these ideas help your diagnosis.

The search for the answer can be difficult, which is why you should take your time and not jump too quickly to any conclusions. Let the evidence point you in the direction.

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One Comment

  1. Definitely check the cooling system! You mentioned white smoke, which goes away quickly after start up. Borrow, or buy a cooling system pressure tester, and pressure test the system. Don’t exceed the system pressure by to much (pressure value on radiator cap). Never remove the cap when under pressure wait until the engine has cooled enough to safely remove it. Coolant maybe entering the cylinder while the engine is cold, parts expand at start up and seal it off. Pressure test it overnight and note any big changes in pressure. You may even pull spark plugs first in the event coolant finds its way into a cylinder. Good luck. Cool ride by the way.

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