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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 08-24-2012
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Cyl. Heads

So I pulled out my heads today, and was going to get them pressure tested. I am looking at about 400 just to test. Autozone is selling them new for about 350. So now I am looking at just replacing them and not spending 400 for the test. Any one know of a good place I can look for them decently priced with good faith that they will last?
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Old 08-24-2012
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What makes you think its the heads that are bad?
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Old 08-24-2012
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About a month ago I overheated heading home from Berkely. I changed thermostat and water pump. Two days later I was driving down to Houston TX from SF California and I overheated heading down I-5. I cooled it off and kept driving after putting more coolant in it. I overheated again stopped at pep boys and changed the radiator cap, refilled more coolant and kept going. I overheated a third time let it cool down and I removed the thermostat and then started heading back home. I have water in my oil and spark plugs are not looking too hot. In your experience would you think I shouldnt bother replacing the heads? If odds are its the gasket I will be more than happy to replace that. But I just think over heating it 3 times in the span of about 5 hours is not in my favor.
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Old 08-24-2012
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If you have an ohv they are known to crack around the exhaust valves in the center cylinders.

https://www.alabamacylinderhead.com/ has the for 245 each new assembled
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Old 08-24-2012
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Blhde is correct, I had a set of 3.0 heads crack in that spot. I wouldnt bother testing them for as cheap as they are to replace. 9 times out of 10 thats the issue is the cracked exhaust valve area
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Old 08-24-2012
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i got push rods
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Old 08-24-2012
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and yea i found some at cylinder heads international or whatever it is for 175 thanks for the info
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Old 08-24-2012
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What is that process called that pushes abrasive compound through the ports to polish and enlarge them? If that is cheap it may be worth doing since you have the heads off anyway.
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Old 08-25-2012
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Porting is normally done with a hand held grinder.

Abrasive compound is used to lap the valves into the valve seats.

Never heard of using compound to port heads.
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Old 08-25-2012
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Quote:
Originally Posted by Ranger Smith View Post
What is that process called that pushes abrasive compound through the ports to polish and enlarge them? If that is cheap it may be worth doing since you have the heads off anyway.
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Originally Posted by Blhde View Post
Porting is normally done with a hand held grinder.

Abrasive compound is used to lap the valves into the valve seats.

Never heard of using compound to port heads.
Ranger Smith is correct, there is a process where you push through the port a thick mixture of abrasive material and it smooth things out, how much it will take out as enlargement of the port I am not sure but there was a process.

The old tired and true method of porting heads with a grinder is an art not something just anyone can get right, anyone can do it but will they can hurt more than help.

Porting heads may help some but the polishing is not needed on a street engine, actually what happens is the ports get too smooth and the air/gas doesn’t move around enough and loses the mixture, gas and air separate and doesn’t give you as much power. You lose power in the long run unless the engine is turning higher rpms.

My 2 cents, keep them stock unless you have a reason for the porting/polishing.
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Old 08-25-2012
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Grev that is spot on. The port matching and taking out a few obvious restrictions is ok but the polishing does create an issue. You need that rough surface to create turbulence within the intake runners. A full out polish job is usually meant for carb motors where the mixture has already happened.
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Old 08-27-2012
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will it be possible to visually inspect the head and see a crack if one existed? at this point i have too much time on my hands so I am going to put new gasket and take my chances and go from there
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Old 08-27-2012
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Its possible depending on the size and location of the crack
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Old 08-27-2012
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With the cost of head bolts and gaskets I would be damn sure the heads are good before I put them back on.

Normally the truck losses coolant and there is no visible leak. Also the spark plugs in the bad cylinders show signs bad things burning.
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