1. Oil Pressure. How many miles on the engine? Oil pressure tends to drop as mileage goes up or from improper maintenance. The tighter the tolerances on the bearings and such will give you higher oil pressure, plus a good oil pump will help this out. If your engine is high mileage I would say you might start at the oil pump, or it could need rebuilding.

 

2. Gurggling. I would replace that cap and see what happens. Also check your antifreeze/coolant mixture. Do you have a tester? Go get one at the parts store. you need a 50/50 mix. Too much water and it could boil more easily, especially if you have a faulty cap. That cap holds pressure in the system to help raise the boiling point of the coolant.

 

It will show fluctuations. Mine does the same thing since new. The lower the idle the lower the pressure. The higher the idle, the higher the pressure. Make sure the fire didn't damage the sending unit if you didn't replace it. If you are in doubt about your actuall pressure. Install a mechanical gauge temporarily and check. Minimum pressure is 10 PSI for every 1000 RPMs.

The cap has a pressure and heat sensitive spring keeping the pressure constant. 13PSI. Pushing coolant to and sucking coolant from the overflow bottle is normal.

If the fire was close to the radiator cap, it could have ruined it. Replacing the cap is relatively cheap. Also make sure the coolant is at the right level. About 1/2 inch to 1.5 inches below the cap.

Do a computer diagnostic.

Some parts are not compatible with each other even though they will fit and plug in. Make sure the 1990 part matches the 1986 part, including part numbers and engineering numbers marked on the part. If they do not match, cross refference the part numbers to your application to see if it's compatible. Also could the fire have damaged the part?

This is possible due to the fire warping parts. Check by spraying water mixed with soap around the intake manifold and the throttle body gaskets and looking for air bubbles. You can also use a hose held to your ear, like a doctor's stethoscope. Hold one end of the hose to your ear and the other to probe for hissing sounds.

The PCV valve is normal to suck vacuum through it. The PCV valve's function is to control the amount of vacuum that is applied on the engine's crankcase. There is a spring inside the PCV valve. If the fire got close to the valve, it could have warped the spring inside, so changing it would be prudent.

 

Why would you want him putting water on vacuum lines? Thats dangerous and no offense, really bad advice. Sucking water into your engine can harm it. Only use this trick when you check for leaks on POSITIVE pressure systems like your tires. The soap will form bubbles only when blowing out of the part.

Try using small quick bursts of propane around suspected leaking intake parts. If the idle suddenly changes then it is leaking and sucking in the propane and burning it in the combustion chamber. Water doesn't burn in your combustion chamber. Make sure your engine isn't too hot when using propane, as there is an explosion hazard if you just let the propane out too much on a too hot manifold.

 

or use carb cleaner

 

Soapy water from a spray bottle. We are not talking a lot of water here. The amount is small.

This is a time tested technique, not something I just made up out of a whim. It's safer than propane and any other excelerant.

The worst that amount of soapy water from a spray bottle will do is decarbonize his engine, if that, and will most likely vaporize before it hits the cylinders anyway.

There is water in our atmosphere. We breathe it even. Water vapor is sucked into the intake all the time through the carb air horn. Especially on cold days you may see water droplets dripping out the exaust. How did that water get there? Through the intake, through the engine, then it condences and drips out the tailpipe.

It's not like filling the engine cylinders with water and trying to compress the water on the compression stroke. Liquid water will not compress, therfore will break pistons. The only way he would be able to do that is put a garden hose down the carb air horn.

Since he just had a engine fire, I'm reluctant to suggest to tell him to do anything that would even remotely start a fire. This includes using propane, WD-40, Carb Cleaner, gasoline, or any excelerant whatsoever.

Soapy water from a spray bottle is safer and with the amounts being discussed will do his engine no harm whatsoever. There's probably more water in his fuel system from the gas station, than what he can add through a spray bottle through an intake leak.

 

Thanks for the replies so far guys.

I've heard both sides of the propane and water from my friends. I tend to go towards soapy water first and if I can't find the leak and am still sure there is one I try propane. I am going to be buying a new IAC valve (I cross referenced the part numbers and they are not compatible), swapping out the rad cap, and buying one of though triple gauge clusters that look nice because I'm tired of removing my water temp gauge when I want the truck to look nice because coolant comes out.

I will post this after. I do also have a code reader... somewhere. I can also read it through a voltmeter but that is a pain.

Question about the pcv valve. I have this model and am wondering if a vacuum hose that feeds into the intake manifold should be connected to both or just one of the openings. (I know the bottom is required wondering about the top.)

-Dimitri

 

Just reading this again. Check the PCV valve grommet where the PCV valve slips into the valve cover. These are prone for oil damage and if it's bad will cause a severe vacuum leak.

 

Soapy water isn't my first choice either, as it's not that effective.

The hose to the ear, "poor mans stethoscope" method is my first choice.

Although I have used excelerents as well to find leaks, I just don't feel comfortable telling you to do that in this case.

The hose to the ear method is the absolute safest way.

As for the IAC valve. Replace that part before you go any further with diagnostics.

The top port is hooked to the canister purge solenoid or valve. This canister purge solenoid or valve purges the charcoal canister of accumulated gas fumes collected when the truck was off. It uses the top port of the PCV valve for vacuum.

As I said in my last post, check the PCV valve grommet. It might be defective as well.

 

Someone please tell me what the point is to the soapy water? Soapy water on a vacuum line will do nothing. You put soap in the water so that it makes bubbles right? Will you please tell me how a vacuum is going to blow you a bubble? Im sorry if I upset anyone, but I really think thats a stupid idea, even if it doesn't hurt your engine, it is still pointless because it doesn't show you anything.

Oh, and water in your exhaust is not caused by sucking it into the engine. Combustion of gasoline gives off Hydrocarbon, Carbon Monoxide, Carbon Dioxide, water (thats H2O), and NoX's. Water in the exhaust is also caused at startup, when hot gases hit the inside wall of your cold exhaust it causes the above stated H2O to condense inside the pipe.

Dude...don't listen to the soapy water on your engine thing. Its bogus. Ive used propane for years, its much safer. Use small quick bursts near a suspected leaking part. Wait a minute, let the propane dissipate, then try again. As long as there isn't anything in the engine sparking near the gas or an open flame and you keep the hose from your propane tank near the part and use short quick burst you wont start a fire.

Soapy water on a vacuum line?? Just think about it...it makes absolutely no sense to do that.

 

Ray,

It's never a bad thing to question authority but I just wanna letchya know that 81-F-150-Explorer is one of the industry experts here on this forum. He is more than twice your age and has decades of professional experience dating back to well before you were born.

When he talks, people listen.

Even though what he proposes sounds backwards and pointless, he is the expert here. If he says this works, then it must somehow work.

I'll let him answer in more detail.

 

Please explain. Because it makes no sense to me. Ive been turning wrenches and have restored five cars in my short years. 1969 VW beetle, 1970 Chevelle SS, 1931 Chevy two door sedan, This 1986 F-150, and a 1970 Nova. Not to mention I am the family go to guy for mechanical problems. I rebuild several engine and routinely troubleshoot problems for everyone I know. When I talk, people listen as well. All I want to know is how putting soapy water on a vacuum line tells you anything at all. All its going to do is suck the soapy water into the line. The soap is pointless here if you are trying to use it to see bubbles or something. 81-F-150-Explorer was wrong about the water coming from your tailpipe as well. yes, some comes from the air, but most is from condensation of the by product of combustion.

By the way, I am a robotics engineer/draftsman for a multimillion dollar corporation. (i'm trying to build credibility here since I don't have 6,000+ posts) I can afford to go buy a new truck, but I prefer the challange of fixing old cars and trucks because it hones my skills and lets me know what systems or designs not to use in anything I design. My involvment on this forum is for the purpose of gaining knowledge on how these old trucks work, and for sharing what I do know about mechanics. I will admit I have alot to learn, and I think its wise consider that the number of posts you have on an internet forum is not directly proportional to your knowledge.

Cheers

 

I will admit it wont show you much, and you will have to be looking close for it. It will suck or blow a small amount depending if it's negative or positive pressure. You can see this with the naked eye.

Your forgetting the water in the air. Water in our air varies with the humidity. On a real foggy day you can actually see the water content. This water in a gasous state goes down the carbs airhorn. As you say when the hot gases hit the cold tailpipe it condences. Part of that water comes from the combustion process, part of it comes from the air that is sucked into the carb, part of it unfortunately comes from your gasoline, and part of it comes from the air that went up the tailpipe with the engine off.

My point was that there is water in the combustion areas of the engine and intake normally, not how it got there.

Well don't take my word for it, as I said I did not make up the technique.


Here are several ways of using soapy water to find a vacuum leak. One of these tests is from an ASE certified mechanic...

Signs of Intake Manifold Leaks | eHow.com
How to Check for Vacuum Leaks | eHow.com

 

How was I wrong? You even admit some water comes from the air in the same paragraph. My whole entire point which you seem to have missed was that there is water in your combustion chamber and intake manifold, and even exaust pipe. Which I explained better in my last post. This water does no harm to your engine, as there is a lot more in there than you can really add with a spray bottle, so adding a little is not going to hurt anything.

This all started with your fear of damaging the engine with the soapy water. When I tried explaining to you there is water already in the combustion chambers and intake, and the water you add with a spray bottle is negligable, you seemed to switch tactics.

It seems to me, you are trying to build your credibility by destroying the credibility of others. If this is the actual case, it will not work and make you look bad.

If this is not the case, then I suggest you change the way you articulate your views, as it makes you seem abrasive and contemptuous, at least to me.

 

81 F150 Explorer, in post #18, you advise to spray soapy water and look for bubbles in order to find a vacuum leak. When I first read this, I was saying "Whaaaa?" in my head.

I believe Ray1986 did too. I think Ray was just looking for a concession to the point that a vacuum leak will not blow bubbles.

Both procedures will work to find a vacuum leak. The indicator is not bubbles-- it is a change in the way the engine runs.