replacing a head gasket
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From: Cross SC
replacing a head gasket
I've got a '85, F-150 l6 that I think has a blown head gasket, Can any one tell me how to check this out( other than water in the oil). If it is blown how do I go about fixing it?
Also,I need to drill out an exhaust/intake stud hole, that is 3/8" w/24nf, to the next size up,maybe to 7/16" w/24nf threads, anyway what size drill do I use? I figured that while I have the head off it would be a good time to fix that leak.
Also,I need to drill out an exhaust/intake stud hole, that is 3/8" w/24nf, to the next size up,maybe to 7/16" w/24nf threads, anyway what size drill do I use? I figured that while I have the head off it would be a good time to fix that leak.
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If you have a blown head gasket your engine usually will run hot, you'll lose coolant either into your oil, milky colour or into your exhaust -white smoke -lots of it -or you'll notice air bubbles in your coolant if you take off the rad cap with the engine running. As for the bolt re-thread use a 13/32 drill for the 7/16 threads.
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From: Cross SC
Thanks for the info, I know how to tear it down ( i'm good at tearing things up or down) it's the putting it back together that I always need help with, Any help or advice would be greatly appreicated. What kind of gasket would you recommend? Do i reuse the same head bolts?
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take a real close look at the head gasket when you pull the head it can tell volumes about what is happening with the engine . Try to see where it failed. If you can't clearly see a fault with the gasket look for a cracked head ( 300s are known for cracked heads) and I would suggest looking at your plugs the cylinder at fault if the blown gasket is occuring at a cylinder should show up on the plug. For instance if one plug is very clean compared to the others there may be water getting into the cylinder and steam cleaning the plug. By all means use the bolts again but make sure you chase the threads in the block with a tap before reassembly and either use a recommended lube from arp or 10/30 when you torque them up also put some on the shoulder for even torque values. I would use a Felpro gasket dry.
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From: Cross SC
Man, you guys are good. Thanks. About the lube, I don't know what they are, can I use anti-seize? I've gotten into the habit of anti-seizing damn near everything..... well almost everything.
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From: Langhorne, PA
Yo smitty7, I did a fun thing today. On my I-6, I tested the compression of each cylinder. According to the Haynes book, a comp test will speak to you and give you a good idea what the condition of your engine block is. All I know so far, is that, there is coolant coming down the back of my engine, and from the test I did I suspect cyl. #6 is wacked . cyl.1 to 5 had 150 lbs compression after I cranked the engine a few times. #6 reached only 120 psi max. I think that is telling me I have a crack or bad gasket near #6. I hope you can try doing a compression check before you rip it apart. It might give you some insight, it did for me.
PS can you write us back, I need to know what you had to buy, what you may have re-used and what the problem areas might be.
PS can you write us back, I need to know what you had to buy, what you may have re-used and what the problem areas might be.
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From: Cross SC
I'll be glad to write back and the good part is that I just did the manifold's, I don't even have the hood back on yet.When I first cranked it up to test it for leaks, I noticed a lot of white smoke coming out of the tail pipe and then a it ran hot. I replaced the thermostat, water pump,new fan and flushed the radiator and it still runs hot. Tomorrow I'll drain the oil and check that, if that's okI've got new plugs to install anyway, so I'll check them for extra clean, right?
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From: Cross SC
Had a chance to pull the plugs and they all look dirty, like used plugs, none are too clean. So if I get a chance tomorrow I'll change the oil and look at it for water mixed in.I there is no water in the oil what then, a compression test?
