I recently bought a 1980 F250 4x4 for 600 bucks. The guy that had it before me dropped a 1974 460 in it but left the old radiator in it. The first couple of days that I had it, I drove all over the place and didn't have any problems except running out of gas. However, yesterday I drove about 5 miles and noticed a strange smell. Then the truck started missing out when I hit the gas. I pulled over and let it sit and it idled just fine. About an hr. later I tried driving it again and it did the same thing after about 5 miles. When I checked the engine the coolant was foamy, and the stuff in the reservoir had a film on it. Is it just getting too hot? A friend said I might have a cracked block.

 

Time for a compression test of the cylinders and maybe a pressure test of the cooling system.

Foamy coolant is not normal, could just be air in the system but not a good sign.

Old fluid may have a film on it so depends on how much and how old whether it is a symptom.

Do a compression and tell us what you see.

You don't want to see two cylinders next to each other with a low compression. You don't want low compression on 1 either. But two often means a bad head gasket.

While the plugs are out, take a good look at them. Sniff them too. Tell us what you see or smell.

Check the oil filler cap and dip stick. If there is something that looks like pudding on them, you have a problem or it has just been driven cold all the time and never allowed to warm up.

Good Luck,


Jim Henderson

 

Thanks. I am at school right now, but I will try and get on that this weekend. How would I run a compression test? What all does that entail?

 

You will need a compression gauge. Most parts stores have them. I prefer the kind with a threaded adapter. Others come with a rubber nipple. The reason I like the threaded is that once it is screwed in, you can run the test by yourself. With the rubber nipple you need a buddy or a remote starter.

abuddy who has some mechanical skill may be worth bribing with pizza to help you.

Since it sounds like you are fairly new to mechanics I will state what should be obvious... Keep your hands, clothes hair etc away from ANY moving parts, like belts, fans etc. The engine should not start but you don't want surprises. that's another reason I like the screw in guage, you aren't anywhere near it when you run the test.

To run a comrpession test remove all the spark plugs. Usually you also need to disable the ignition coil/distributor. On older distributors I just removed the main coil wire. On the electronic ones it depends. Check a shop manual or ask around. I am not sure how to do it or if you need to do it on your model year.

Get yourself a note pad and write down the compression figures for each cylinder. I think some guy said all Fords cylinder numbering is 1234 on the driver side and 5678 on the passenger, front to back. I would need to check to be sure. Main thing is you write it down and know which cylinders the readings apply to.

Make sure you are in park and out of gear. Then plug in the guage and crank the engine. You want to try to keep the same number of revolutions. You can tell by the thumpa thumpa wheeze sounds you will hear. If you are using the rubber nipple guage, have your buddy turn the starter while you watch the guage and count turns.

Write it all down and post the numbers. These first numbers will tell you if you have bad piston rings, head gaskets, cracked valve guides or lord forbid a holed piston.

While you are doing the test keep an eye open for clouds of water blowing out of one or more cylinders, not a good sign.

The next test helps narrow down between rings and everything else. Take a squirt can of engine oil and squirt a single good squirt of oil in ONE cylinder and then run the compression test. If the number goes, up you probably have bad rings. If it doesn't, then it is one of the other problems.

Your results normally will be all cylinders within a range of 10% or so of each other. For example the readings may be 120 110 125 115 115 126 120 110. Depending on your model and age of engine this would be a low normal spread of compression readings.

What you don't want to see is something like... 120 90 90 125 115 120 110 0

The two 90's would indicate a bad head gasket. The 0 would probably be a holed piston. You would probably know you had a holed piston without the test tho.

Good Luck and post the readings,

Jim Henderson


Good Luck,

Jim Henderson

 

Thank you so much. Like I said, I will try to get that done this weekend, then I will let you know how things go. I really appreciate your help, this is a great site.

 

Good job Jim.

Of course it doesn't matter for the compression test, but you did get the cylinder numbering backwards. 1,2,3,4 is passenger side. 5,6,7,8 is driver side.

Might be important if he pulls the plug wires without marking them.