Alright guys this is driving me nuts. I have an 1990 F150 with a 302V8 M50D trans. Im pretty sure i have a bad head gasket and im hoping for someone to tell me im wrong but here is whats going on with the truck: Tailpipes smoke for a little bit after i shut it down. It leaks oil slowly it drips off the bottom of the bell housing, right when you turn the engine off and you hear a sucking noise like a piston pulling in air. when its cold sometimes it misfires when you start it and it wont run normally till its hot.(it acts like a cold two stroke motor) The truck has never died or overheated for the 6 months ive had it but i think it has had a considerable loss of power since i got it. I would also like to know if it would be a terrible idea or not to dump some head gasket fix in there. oh and i found out the truck has no pcv valve there is just a hole in the valve cover where its supposed to be

 

I would start with putting a pcv valve in asap. Next, check the back of the intake manifold and valve cover gaskets for oil leaks. Both of my valve cover gaskets and intake manifold gaskets were bad and leaked so much oil I thought it was a rear main seal at first. Then check your timing.
If it's not blowing smoke or leaking antifreeze from the tail pipes it's hard to say the head gasket is bad. Also, check to make sure all of your vacuum lines are A. in good shape, and B. hooked up.

 

could also do a compression check.... that will give you a better idea of the mechanical integrity of motor. Is there any motor oil smell in radiator? any condensation (or milky looking stuff) under oil cap?

I also agree with putting in PCV because that does have a huge impact on runnability

 

Have the engine running at operating temps, and while it's idling, take the oil fill cap off, that is a sure way to tell. If you feel a puff puff puff pressure coming out and smoke/steam, you have a blown head gasket.

Is your oil turning into coffee looking slime? Any oil/coolant lost, or mixing in your radiator? These are all other ways of looking for head gasket problems.

 

Alright so i was just outside and i started the truck and took the oil cap off. Bad news. There is a buildup of white residue and its steaming/smoking. Although i cant feel any air puffing out. I dont really have the time or money right now to pull the engine out and fix it. I will be able to do it however at the end of may. What are your thoughts on the temporary solution of putting head gasket fixer upper stuff in there. Since the motor starts and runs without a whole lot of problems i would think that the gasket leak cant be very large. If anyone has used that stuff before i would appreciate some information about it and what its gonna do internally to my motor.

 

I wouldn't waste money on those gimmicky products. Your going to be rebuilding it in a month anyways so why not just continue to drive it until your ready to get at her. Just my .02.

 

Continuing to drive it is only done if an entire new rotating assembly is going to be installed.

Antifreeze in the oil will destroy bearings and the camshaft. Just putting this out for reference. YMMV.

Ray

 

ray is 100% correct.... park it up and take out the oil so the bottom end bearings aren't sitting in antifreeze. Coolant just eats them up quick. then knocking comes......


sorry to hear the bad news

 

Thanks for the advice everyone

 

I would be inclined to actually do tests on it and confirm a bad head gasket.
You stated there wasn't a PCV valve installed. If this is correct, then you are going to have white residue and steam/smoking exiting the oil fill with the cap exposed. Purchase a Motocraft PCV valve ($8), then check hose from PCV valve to ensure its not blocked, then connect it to plenum. This wil help pull excess gases and moisture from the crankcase as it builds pressure. Drive the truck, get it warmed up, and then check. Look for coolant reservoir to see if it overflowing. That is also a sign of bad head gasket. So far, I'm not convinced of a head gaske problem.

If you wanted, after getting truck good and wamed, 25-30 mins, then park it, and drain oil in clean drain pan, and look for signs of coolant. You'll know if it has it. Then if you want, just refill with oil you drained or spend $15 on 5 quarts of fresh 10 or 5w-30, and Quality filter, no Fram, and then drive till May.

Just a few thoughts...

 

^^ what he said.

With the issues you've described, I wouldn't immediately assume it's a head gasket issue.

Along with installing a PCV, I'd recommend to check compression, and also pressurize the cooling system and watch for a drop in pressure. I'd also recommend checking the plugs, wires, distributor cap and rotor. Condition of the plugs can tell you a lot when diagnosing.

 

There are head gasket leaks and there are head gasket leaks. What symptoms you have and how bad it is depends on what's leaking to where.

Head gaskets have to keep 5 different things from leaking to or from the others:

• Cylinder pressure - vacuum during idle intake stroke, very high pressure during compression and power strokes
• Coolant - pressurized, but not very much
• Oil - being pumped up to the rockers, pressurized but not very much
• Crank case pressure - the space where the push rods go down into the block, PCV tries to make this a slight vacuum
• Outside air - none of the above stuff is supposed to be able to leak outside the engine.

Most leaks probably involve a cylinder since that's where the most pressure and heat are. If it leaks to the crankcase or the oil you get the puffs out of the oil fill cap. If it leaks to the coolant you get bubbles at the radiator cap and cruddy looking coolant.

Sometimes coolant leaks into a cylinder. That gives you white puffs in your exhause as well as a really clean spark plug (a case where clean isn't so good).

Coolant leaking into the oil will wreck your lower end (as already discussed) and will show up as water in the oil or condensation on the fill cap (although moisture can get in normally as well and will collect on the fill cap if the PCV isn't working well and/or the engine isn't run long enough to warm up and dry itself out).

Oil into the coolant shows up at the radiator cap since the oil is lighter than the coolant.

I know I've left some things out, but take this for what it's worth.

 

I'll add this;

1) Coolant in the oil - makes your oil look like a chocolate milkshake.

2) Oil in your coolant - you will actually be able to smell motor oil in your radiator. Some milkshake appearance to the coolant.

I would try a new PCV valve. With the engine warmed up, you would see/feel a puffing effect at the filler if you really did have a blown head gasket. A little vapor coming out of it at idle might not be bad. You're concerned with a puffing effect in time with engine speed. What you observed at the oil filler (condensation, etc) would be correct for a motor with no PCV valve.

Check the plugs! One plug will be very clean if you have a blown head gasket. You will also see a drastic loss of coolant, like having to fill the radiator every few days. Also, leaking combustion pressure will force coolant out of the radiator and into the coolant overflow bottle. That coolant will have a bad/odd smell to it from combustion residue.

You know, as I typed this, I went back and re-read your posts. Maybe you just need a tune-up. How long has it been since you did that? I think I would do a tune-up before I began to panic.

As far as that oil dripping, sounds like you need to do some gasket work.

I'll throw that out as food for thought.

Ray

 

I checked the coolant and its bright green like the day i put it in and there is no oil smell in the radiator. Also i checked the oil and its still full and looking at the spot where i usually park it it seems that there is no longer an oil leak. In fact there is a little too much oil in it. Im going to start with installing a pcv and then checking all the spark plugs, wires cap and rotor...etc thanks for your help everyone i always learn alot from this site.

 

Well, maybe the panic is over. Give your truck a simple tune-up (maybe a six-litre tune-up) and go from there.

Good luck,

Ray