1991 Ford Pickup - Water from Tailpipe

A short block is an excellent choice

Agree, and would like to ask that if the lower engine portion is fine, machining the head to make everything straight again can be compensated by a little oversized head gasket, not affecting compression ratio that much. But you could make this increase in compression usefull....

You could have water in the oil. A white floating foam is a sign. Or, oil in the coolant. A scummy substance will be floating on top of the water and will be sticking to the radiator cap.

Neither is a good sign. You should not have to add coolant that often, so do as PWSlack has suggested.

No there is no water in the oil and the engine dous not burn any oil between changes it also does not mark its territory. It also is not chocolatey so my conclusion is no water in oil.

I'll check the cap this morning... that clatter I'm talking abaout is intermittent and did not even happen yesterday morning but I here it start and stop from time to time So your theory of a valve seat sounds logical as it may not slam into place all the time or would it? Never the less I think I will take it to a mechanic on Monday.

Thanks

James are you the OP?

The 4.9 Ford six is a pretty tough engine. You don't say how many miles and the type of use it has seen. Some things to note: The clatter when first started is usually solved by changing the oil filter (the oil filter has an anti-drain-back check valve that can fail in the cheaper oil filters). Second, some water and vapor out the tailpipe is normal and should disappear completely when warm. Third, coolant loss can be due to a leaking radiator cap or a very small leak above the liquid line were vapor comes out only. Does you vehicle have a recovery reservoir? it should. Is there an odor of coolant around the vehicle or under the hood. You could have a leak that evaporates on the hot engine. The coolant system can be pressure checked and this will show the leak or if it does not show a leak then most likely the radiator cap is the problem. I would not replace or rebuild until i knew for sure what the problem is. Hope this helps.

That sounds good I will start with an oil filter and radiator cap and see what happens, Some times it's the simple stuff...

it has around 177,000 miles and has just been the family truck My uncle had it when it was 1yr old and my cousins drove it in high school and then I got the nephew deal a year and a half ago when he upgraded to a 95 with a V8.

I mean the thing is a runner freeway at 75 no problem never any oil under where it parks starts right up every morning, just got that dieseling noise once in a while. and a leak on the exaust tube that runs under the intake "emissions thing" but other than that I drove it from Portland to Seattle a dozen times or more last summer.

It's highly likely that the head gasket has failed and is leaking coolant into a/several cylinders when cold. When the motor sounded like a diesel it was either from the liquid in the cylinders failing to compress and probably bending some connecting rods or from detonation caused by inadvertent water injection with resultant detonation. Either way there is serious damage to the motor's bottom end. You could probably get away with rebuilding the bottom end and doing a valve job on the head. Just make sure the crank is straight, the rods are straight and the pistons are still oval. Bob

What are talking about? He says it only clatters sometimes, and that he started it just the other morning and had no problems. If the connecting rods were bent, I think there is no way it would run even remotely correct; it certainly would be horrible to drive, and he wouldn't have to ask about it. Also, if the cylinders were full of water, wouldn't this simply hydro lock the engine? Obviously, it depends on the engine rpm and amount of water in the cylinder, but if several cylinders had water, then the engine is making almost no power (since each one is contaminated, there is no good combustion happening.) So then I think that the engine would certainly hydro lock instead of bending rods. (Although that might be possible.) And, what is the "water injection" you're saying could cause detonation? The only way that would occur is if the mixture was leaned out...so, the engine is putting out the correct amount of fuel to air regardless of the water issue...are you saying the water is atomizing? It won't ignite, and its not separated into its respective H and O molecules, so what effect would it have on combustion?

Your correct.

Not only would the spark plugs be fouled in the morning making it impossible to start, but a hydro-locked engine will not turn over and you would force the compression into the coolant system and force the coolant to leak into the engine oil. There would be signs of brown foam on the dip stick, and back flow pressure in the radiator.

I don't believe the problem is the cylinder head gaskets, and would recommend a compression test to confirm my statement.

The coolant can be drained and all spark plus removed when performing the compression test. But I still recommend that when the engine is turned over stand back, if there is a large volume of coolant in the cylinder it will be under a lot of pressure during starter rotation.

Best Regards,

Tim

You can purchase a used engine from a junk yard. Be careful who you buy from.

Otherwise purchase a rebuilt short block and take the heads to a machine shop. If one is cracked they probably have a used one they can do a valve job on for you. You can also get a rebuilt long block.

Remove the spark plugs after the engine has set overnight as you remove each plug you will find one or two with water or light rust/dampness that will let you know what cylinders have the problem, or you can do a compressor test on each cylinder if you have the tools or have it done at a shop.

The head gasket is a good guess but have the head checked by a shop to assure that you do not have a cracked head at the valve seat area before replacing the gasket if there is no blow out areas on the gasket.

You might check in to a used low mileage replacement that would offer you a savings over having to rebuild the existing engine there are company's that will offer a warranty on there engines.

I had a Datsun 240Z that developed a leak in the head developing very similar experience. Apparently there was a hairline porosity in the casting that over time gave way. I had the head welded and machined flat again after the process. It worked great again after that. It was a little bit of a chore removing and re-installing the head but I didn't have to replace the engine. An added bonus was a slight increase in compression.

The head has a hole or a crack, replace them both with rebuilt heads. It is common in this engine when the thermostat goes bad and allows the engine to overheat... once. This has been the death of many Ford engine heads. If your Ford has over 100,00 miles on it change the water pump, thermostat and antifreeze. Remember to operate the heater once every week or two even in the summer so that the heater core wont rot.

I have a 1990 Ford F-150 pickup with over 350,000 miles on it with the same engine. I have replaced a radiator, heater core, water pump, thermostat, clutch, engine seals, transmission seals, universals, axle seals, wheel bearings (because one went out), entire AC system, seats, shocks, brakes, windshield, door rubber, lights and the, radio. The engine or heads have never been touched.

It has lived on Mobil 1 since its birth. The fluid in the rear end and 4 speed transmission is from Amsoil and both have magnetic drain/fill plugs added. I added grease nipples (zerks) to everything and I use Chevron Ultra Duty II grease. If the engine goes bad I will buy a long block from a reputable vendor.

Reconditioning the head may eliminate the head gasket leak but the increase in intake manifold vacuum will suck oil up past the rings and cause oil consumption to jump dramatically, especially on a trailing throttle.

You can't simply go into an old engine like that and fix just one problem. The suggestions made to toss the engine and buy a used or remanufactured one are well advised.

L.J.

Yes, you are right,

If the compression is with in manufacturer's specifications the engine is worth fixing.

Increased vacuum is created by the downward stroke of each piston through the intake stroke. This is why ring compression is so important for proper fuel flow balance and performance.

Good answer...

Best Regards,

Tim

First, have a mechanic do a pressure check on the radiator.This is an adapter that fits the radiator cap hole on the radiator, and a hand pump is used to increase pressure on the system.A pressure guage is monitored to look for bleed down of pressure due to leakage.If it leaks down, very carefully inspect around and under the water pump.There is a weep hole in the bottom of the pump that allows water to drain if the pump seal is leaking.With a minor leak, the air from the fan sometimes scatters and dries the leak before it can be seen.

Also check for freeze plug leakage.These sometimes corrode and leak.If bad, replace with brass freeze plug.They last forever.

Since your engine runs fine,and only occasionally rattles (normal in older vehicles),use a thinner weight oil.This will allow lubricant to get to the moving parts quicker, especially in cold weather.A 10W 30 should do, depending on local temperature.

Please give us some feedback on this problem.

The only sure thing is to scrap the truck and buy new.

Realistically though there is not a tougher, more durable engine that I can think of than the 4.9 Ford. I would do the inexpensive checks first. Pressure test the rad cap, and cooling system. If you have no external leaks, remove the spark plugs and look at them for signs of rust. If the coolant is entering a cylinder, the spark plug will start to rust when sitting over night. Mark where the plugs came from, and continue to pressurize the coolant system as the pressure drops. After about 30 min. of this, have an assistant activate the starter, and watch for water exiting the plug holes.

Water coming from the plug holes is not necessarily the head gasket or a crack in the head or block. The EFI coolant system can develop a leak and allow water to enter the intake manifold and then enter a cylinder through the open intake valve. I think the coolant enters the intake manifold through hoses, usually 3/8". If you can not find the water leakage yet, try blocking the hoses that bring water into and out of the intake manifold, and see if that stops the pressure drop in the coolant system.

Once you are sure you know where the water is leaking from, it is time for a compression test. Do a wet and dry compression test. You need to know the sealing condition of the rings before you you have it apart without answers.

Your noise may be just low oil pressure on start up from the oil filter, or it could be just lifters that are bleeding down when the engine is parked with that lifter on a camshaft lobe. Test your oil pressure also. Only then can you make an educated guess as to weather to replace the head gasket and do a valve job, or to plan a rebuild of the bottom end also. If you do pull the head, check the ridge at the top of the cylinder. That is the definitive test for reusing the bottom end or not. If there is a ridge deeper than .008-.010" the rings do not have sufficient metal to seal well on. Putting new rings in this worn cylinder will yield short term results. When cylinders are this worn, the correct thing to do is bore the cylinders oversize and buy new pistons. Unless you are doing almost all of the labor yourself, you are going to find that a rebuilt engine will save you money over rebuilding yours. Shop prices, there are loads of these engines out there. Good luck.

PS if someone tries to sell you a pair of heads for this engine, RUN.