well on a recent trip my van overheated and things went down from there well got it home and started to miss out on one cylinder went to start looking for the problem and took plugs out and 4 out 8 was loose and one plug was kind of flaky the porcelin that is wanted to know what could happen with loose plugs and it still gets a little hot before i tore it down head gaskets are still good no oil in water or vice versa but still not shure whats goin on its 302 was runnin great thanks for your help

 

Sounds like it could be as simple as a couple of bad plugs. Why were they loose, threads in the head still okay?

As long as you have it torn down this far, take the heads in and have them Magnafluxed to check for cracks and check the surface for trueness. Might not be a bad idea to spring for a valve job in the process, they might be fine or could use a clean up. At least you'll feel justified for having torn it down.

 

well im thinking the heat and expansion of the head and not enough torque might have been a facter and i dont have it all tore down that far i just have the plenum and the valve covers off have a couple of klacking rockers also just tryin to get it back on the road cheap as possible runs great at 70 just starting off has the miss my question would having the plugs loose like they were and the miss would couse the engine to run a little hotter also runnin pure water since it overheated thanks

 

Hmm, I assumed that since you mentioned the head gaskets are still good, you had the heads off and were able to visually check them. My bad.

At this point I'd do a compression test and then throw a new set of plugs at it, see how it does. Have the heads been off at some point in the past? It would be unusual for the bolts to loose torque. Maybe if it got really hot, but that would tend to cause other problems, like blown head gaskets or cracked heads. It's also possible for the heads to crack in the combustion chambers, sometimes between the valves. I had that happen once on my race car, didn't even know about it till I tore the engine down for routine end-of-season inspection and freshening. It may have been causing a bit of a coolant loss problem and overheating, but the car always ran a bit warm.

Loose plugs could certainly cause a miss, and maybe cause it to run warm. How hot are we talking here? It may be that you have another problem, like water pump/fan/fan clutch, or partially plugged radiator. Address the problems one at a time. Do the plugs first and then go from there.

 

Well I noticed a bunch of junk in my radiator, powdery substance and I rinsed it out as well as I could on the side of the road so the radiator could be my problem. I talked to my neighbor and he said to check the water jackets because they could have rust or something because the engine sat before getting put in my van. Going to do a compression test tomorrow, I know its alot but am I looking for the same compression reading on each cylinder and whats the normal leak down time?

 

Well, you don't need the same compression on each cylinder, it's just that between the highest and the lowest cylinders there should be no more than 15 percent difference.

You have the equipment to do a cylinder leak-down test?

After you do the compression test, if one or more of the cylinders tests low, then you can do a cylinder leak down test to help you determine the cause of the weak cylinder.

You will need a leak-down gauge (about 60 bucks, available at some parts stores) and an air compressor. Here's the basic procedure:

You've already got the spark plugs out since you just did the compression test, right? So now rotate the engine so that the cylinder to be tested is on top dead center and ready to fire. This will assure that the valves are closed. Lock the engine so that it can't turn. A c-clamp or Vise Grips can accomplish this.

Install the leak-down gauge in the spark plug hole and apply air pressure. The gauge will register the pressure drop indicating the percentage of leak. In addition, by listening at the exhaust pipe or air intake system or the oil breather you may hear escaping air, which means one of the components is leaking. For example: air out of the exhaust pipe means the exhaust valve is leaking. By removing the radiator cap and observing the coolant, you can tell if there is a blown head gasket and or a cracked head if there are bubbles.

If you buy a gauge for this, it should come with more detailed instructions, and this is only one method of testing. Good luck!

 

no i dont what will i need i was just going to rent a compression tester tommorow thanks

 

I took so long to add to my post above, you already beat me by answering my earlier question. I really need to learn how to type faster!

 

did the compression test today and got water on the number three cylinder so im just goin to start pullin the whole engine out and call it a day friend of mine gave me a good 302 out of a bronco gonna put her in and get her goin again thanks again for your help

 

Don't be hasty, it could be a cracked head or blown head gasket. Yank the head first and see. You might get away with just replacing it. If it's the gasket, you'll need to pull 'em both, have 'em surfaced and replace the gaskets. You could be back on the road a whole lot quicker and cheaper.

But if the engine is pretty tired, then you'd want to pull it and go clear through it.

 

yeah i got the van and the engine had already been replaced and no clue on how many miles are on it not alot of power and a constant rocker noise from the top end it is kinda tired though and the engine that ive got to put in is a real good solid engine low miles gonna put it in and rebuild the other one. At least thats what im thinkin.

looked for compression data on the net and nothin but the ones i did check had a reading of 150 on them is that good? maybe i will just do the heads if thats a good compression reading

 

I'd go ahead and pull them, look at the cylinders and see what they look like. Look for signs of wear like scoring on the cylinder walls and ring ridge at the top of the cylinder. 150 is okay if they're all close to that. How was #3? Was it lower than the others?

On the other hand, if you have a good donor engine as you say, it might be worth your while to go ahead and swap it in.


(BTW, I condensed your last 2 posts into 1. When you make a post and then think of something to add, you can just hit the "edit" button on the lower RH corner of your last post and it will open it back up again. You can change it or add to it for up to one hour from the time you first posted it, then the button magically goes away! )

 

yeah my wife is on your side about fixing what needs to be fixed and thats it goin to start in the morning tearin into the heads and go from there thanks for the info on the adding info didnt know that thanks I also wasnt shure about the compression reading on number three i didnt get hardly a reading at all even put my finger in the hole while cranking and barely pushed my finger out

 

Let us know what you find. And try to have fun with it. It's always interesting to go into an engine and see what's what. And we're here for ya if you need any more advice.

 

thanks I'll let ya know