'84 GT Vert 302 is ka'put

[ewalker008]

Bought my first mustang back in April. Beautiful Arizona black n gold 1984 Mustang GT convertible with stock 302 HO. Almost 0 rust anywhere, and a fresh paint job. Previous owner put a holley 750 mechanical secondary carb on it (vastly oversized), but I still have the factory 4180. After owning it for a few months and only taking it out once in awhile, I noticed water in the oil. I did a compression test and found that I have only about 75 psi in any cylinder. The car never was a powerhouse, now I'm wondering what I've gotten myself into. I'm currently in the process of tearing the heads off (just got intake off), to check the heads n cylinders out. Any thoughts what I may be in for? I noticed that I had puddles of antifreeze on top of my intake. Any tips would be appreciated.

[REDBEARD]

I have no thoughts but............ I think it sure does look nice. Ironically I live in Tucson, AZ but I am from Winfield, W.V. what part of W.V. are you from?

[ewalker008]

Yeah if it ran as nice as it looks it would be a beast. I'm in the eastern panhandle near Keyser. (middle of nowhere really) I hope to eventually put a set of aluminum heads on it and a mild cam. I don't know if I'm ready to sink that much into it right now though. I really hope that the head gasket is the only culprit, but I think its odd that the cylinders were all the same compression...

[bwguardian]

Look on the door jamb and see what the paint code is...palease!

[WRusco]

How many miles on the car?

Is the compression even on all cylinders?

It sounds like a stretched timing chain or a worn upper timing gear (especially if it has nylon teeth.) Also check the dowel pin in the end of then cam. Maybe bent or broken.

Water in the lifter valley usually means a bad intake gasket at the water ports. Check for cracks or corroded surfaces.

Good luck.

[ewalker008]

The car was originally painted light desert tan (which I have heard is getting back quite rare for an 84 convertible). It has about 133,000 miles on it now. The compression is the same on all 8 cylinders. The intake gaskets weren't terrible but the intake bolts weren't torqued evenly. Some weren't tight all and some were super tight.

[854vragtop]

You might have very little wear on an engine with only 133k miles on it. I rebuilt my 192K '85 5.0L motor last December in my garage and it had so little wear that I was able to install stock size bearings and rings. There was no ridge on the cylinder walls, so I just used a bottle brush hone to re-hone the cylinders. The surfaces of the crank were pristine and the cam bearings were in perfect condition too.

I was originally just going to replace the heads with GT-40P's and install a mild cam, but a friend of mine convinced me that it would be just as easy to pull the engine and tear the engine down outside of the car.

[JACook]

The coolant in the oil may well have come from the intake manifold gaskets, or perhaps what you're
seeing is just from condensation, if you don't drive it much. Was the engine oil milky? Or were you just
seeing milky residue on the oil cap?

How exactly were you checking the compression? Were all the spark plugs out? Cranking compression
is as much about cranking speed as anything, and given your readings are fairly consistent across all
of the cylinders, I wouldn't jump to any conclusions just yet.

The '83 and later Mustang HO engines originally came with a double-row timing set, so an '84 should
not have a nylon-tooth cam sprocket, nor are the chains particularly prone to stretching. If you still
have the valvetrain installed, it's pretty easy to check for chain stretch by just rocking the engine
back and forth, and noting how much it rotates before you feel the resistance increase when the cam
begins to turn.

[ewalker008]

I had milky looking oil on the dipstick. When I did the compression test I pulled all the spark plugs and charged the battery up to make sure I got the most oughta the starter (which I also recently replaced). I do have the intake off at this point. The gasket came off in one piece, but that doesn't necessarily mean I had a good seal. I would've thought I would have seen water under the intake if the gasket was leaking.

I am probably going to finish pulling the heads tomorrow afternoon (work schedule permitting). I will probably still try to check out the timing chain and gears while I'm in the thick of things. I'm hoping the block n heads have a clean bill of health. I think I will take the heads to the machine shop too while I'm at it. They can probably give them a better going over than I can.

All in all, if I have the engine apart now I will at least gain some insight as to exactly what kind of condition its in.

[JACook]

So when you drained the oil, was it all milky? Or does water/coolant come out first if you crack
the drain plug loose? This is important. Milky residue on the dipstick or oil caps can happen in
humid climates when the engine isn't getting thoroughly warmed up before putting the car away.
And it's hard for us to see what you see...

You need to do a bit of forensics on the intake gaskets (really with every part you pull off the
engine. Look at the imprint left by the intake manifold flange, and look closely for any signs
of damage, or signs that coolant was migrating past the gasket. Don't rely on the absence of
visible coolant in the valley. Likewise, when you pull the heads, pay very close attention to
the gaskets. They will tell you if something wasn't right, as will the burn patterns on the piston
tops.

At this point, I'm not saying you don't have worn out rings, just that it's VERY unusual for them
all to be worn in such a way that compression is consistently low across all the cylinders. If
this were my engine, I probably would go test another with that gauge...

[PaceFever79]

Just tossing it out there, low compression across the board can also mean it just needs a valve job. That doesn't explain the milky oil, but it could explain the low compression. It's not uncommon for an older engine to have more than one problem. Like Jeff said, you need to really examine all the parts closely and the evidence should point you in the right direction.