importsmasher

My wife has a 66 Mustang with a 200 6 cylinder and automatic (for now....). We have had it for about 4 years, and I am currently driving this car every day. I have noticed 2 unusual issues with the engine that I am wondering if they are common 6 cylinder issues. First, when you start the engine cold in the morning, the valve train clatters for several seconds, then the oil pressure goes up and it gets quiet. Second, when you drive the car for more than 5 or 10 miles at speeds over about 70 mph, every now and then the oil gauge will just slowly drop to zero. At freeway speeds, I am unable to hear the engine well enough to determine if there is truly no oil pressure, but if you slow down, the gauge will come back up.

Are either of these issues common to these engines? If so, is there a way to remedy them? Again, we have been driving this car for 4 years with these issues, so there's no urgency to me to tear the engine apart (I did do rings and bearings about 2 years ago, and neither issue changed). Plus, I have an 89 5.0 and T5 that will be going in it before too much longer (I hope).

Or is our car just possessed (every now and then, it will also "pop" like a backfire when you crank it and one of the plug wires pops off the distributor...wtf?)?

Thanks,
Importsmasher

2+2GT

First, when you start the engine cold in the morning, the valve train clatters for several seconds, then the oil pressure goes up and it gets quiet.
This is pretty normal.

Second, when you drive the car for more than 5 or 10 miles at speeds over about 70 mph, every now and then the oil gauge will just slowly drop to zero. At freeway speeds, I am unable to hear the engine well enough to determine if there is truly no oil pressure, but if you slow down, the gauge will come back up.
This is not normal. Either the pressure sensor is faulty, or the engine is sucking air. This is either bad or really bad.

Are either of these issues common to these engines? If so, is there a way to remedy them?
Not normal. Depends on what's wrong. You got the right dipstick? Oil may be pooling in the top of the head. If the oil level is not low, check the drains.

Plus, I have an 89 5.0 and T5 that will be going in it before too much longer (I hope).
Why not just put the T5 in now, on the 200? Better acceleration and better gas mileage. What's not to like?

Or is our car just possessed (every now and then, it will also "pop" like a backfire when you crank it and one of the plug wires pops off the distributor...wtf?)?
The wire clip is loose, and maybe the cap, too. Try replacing the cap. Check the rotor, too, the clip that keeps it tight may be mashed or missing.

Eagleboo

I've been driving a '66 with 200 6 cylinder since 1983. I haven't had much valve train clatter when first starting, but it has always taken several seconds for the oil pressure gauge to come up. Still makes me a little nervous when I haven't driven it for a while and see the gauge at 0 when I start it...
As far as the oil gauge dropping while cruising, I have never experienced that. I would definitely make that the priority of the 2 indications.
Sounds like "2+2GT" knows his stuff....good luck.

1slow67

I've only of those and that is the clatter. It wasn't constant, but is now gone. Never had a problem with the oil pressure though.

importsmasher

Thanks for the replies. I won't worry about the cold starts, but I don't know what to do about the oil pressure issue. I typically drive the car to work, and it's only 5 miles, no freeway, so it's not an issue on a daily basis, but I would like to figure it out....

When I did the rings and bearings, I also replaced the oil pump and pickup tube. The oil pan was clean, and I didn't find anything out of the ordinary. I even tried running it with an extra quart of oil, but no difference......Again, I will probably just live with it until I gather the rest of the parts to put in the 5.0/T5.....
Thanks again,
Importsmasher

2+2GT

Just bear in mind the T5 can go right onto your 200, while the V8 will require replacing, well, everything but the body. The T5 could be installed in a Saturday, or an easy weekend, but V8 conversion is a very big deal. Find out what's going on by installing a real pressure gauge, the kind that uses a capillary tube from the engine to the gauge. Cheap at any auto store, and then you will know what's going on with your engine pressure.

importsmasher

2+2GT, I may have to do as you suggest and put a gauge on it. For the time being I am only driving it around town, and keeping it under 70 on the freeway.

As for the T5, I would still have to find a bell housing and flywheel to mate the T5 to the 200. I have most of the parts to do the V8 swap (89 5.0 engine complete with wiring harness and computer, 9-inch rear, Granada disc brake setup, V8 springs, motor mount brackets, etc), with the exception of a few smaller items like clutch linkage and a fuel pump to feed the injected motor. What I don't have at the moment is time or a place to work on it....I am hoping to close escrow in the next few weeks on a new house with a 1600 square foot garage...then I will have a place to work on it.

Thanks,
Importsmasher

2+2GT

Looks like you have a handle on how much work it will be.

tx65coupe

I did the I6 to V8 conversion on my 65 and it is quite a bit of work, but is not that bad.

Ferreira

What's the preferred engine oil for the I6 ?