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Old 01-12-2006, 04:18 AM   #1
Godlaus
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Head Gasket Replacement

About to replace the head gasket on my 1990 3.8L Taurus GL.

I plan on replacing the PS hoses and the valve gaskets at the same time to save time and replace the achilles heels.

But, my dad tells me that I'm going to have to send the heads out to machine them down, because after a head gasket goes, it creates an imperfection in the heads. Is this true? Am I going to have to spen another 500 bucks to machine the heads down?
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Old 01-12-2006, 04:22 AM   #2
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Quote:
Originally Posted by Godlaus
About to replace the head gasket on my 1990 3.8L Taurus GL.

I plan on replacing the PS hoses and the valve gaskets at the same time to save time and replace the achilles heels.

But, my dad tells me that I'm going to have to send the heads out to machine them down, because after a head gasket goes, it creates an imperfection in the heads. Is this true? Am I going to have to spen another 500 bucks to machine the heads down?
Well, it wouldn't make sense that you could "machine the heads down" due to an imperfection, cause wouldn't machining them down cause an imperfection? Or maybe I don't quite understand what they mean by imperfection.
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Old 01-12-2006, 04:23 AM   #3
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Quote:
Originally Posted by jedimario
Well, it wouldn't make sense that you could "machine the heads down" due to an imperfection, cause wouldn't machining them down cause an imperfection? Or maybe I don't quite understand what they mean by imperfection.

The coolant is forced in between the block and the heads, and may cause an "imperfection" in the heads. Machining the entire bottom of the heads would correct the "imperfection" that would let coolant leak past the head gasket.
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Old 01-12-2006, 04:26 AM   #4
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Quote:
Originally Posted by Godlaus
The coolant is forced in between the block and the heads, and may cause an "imperfection" in the heads. Machining the entire bottom of the heads would correct the "imperfection" that would let coolant leak past the head gasket.
OK, so as long as the head is smooth it's ok, it can be shorter than it used to be?
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Old 01-12-2006, 04:27 AM   #5
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Quote:
Originally Posted by jedimario
OK, so as long as the head is smooth it's ok, it can be shorter than it used to be?

That's what I presume when my dad was telling me that it needed to be machined.
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Old 01-12-2006, 04:43 AM   #6
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Quote:
Originally Posted by Godlaus
About to replace the head gasket on my 1990 3.8L Taurus GL.

I plan on replacing the PS hoses and the valve gaskets at the same time to save time and replace the achilles heels.

But, my dad tells me that I'm going to have to send the heads out to machine them down, because after a head gasket goes, it creates an imperfection in the heads. Is this true? Am I going to have to spen another 500 bucks to machine the heads down?
Just because the head gasket(s) let go doesn't mean you need to have the heads resurfaced. If it was severely overheated, then yes, resurfacing is in order. The only way to know for sure is to measure them for distortion. The heads on your 3.8 need to be within .006" lengthwise and .002" across. Odds are you don't have the proper tools to do this, and even though it's easy to measure, the correct machinists straight edge costs at least $100.

So it's time for a trip to the machine shop. You could have them measure them, but 99 times out of 100 they get shot down. So just tell the machinist that you're replacing your head gaskets and want them resurfaced. Should cost you about $30 for the pair. Warning! It will cost you more if the heads are dirty, if there is old head gasket material on them, or if any parts have to be removed for them to lay in the resurfacing box. The easiest way to test for this is to lay them on a workbench. If they lay flat, you're good to go.

Finally, when you get them home make sure you wash them. Lots of hot sudsy water is what you need. I use cheap dish soap, a bottle brush and a tooth brush. DO NOT rely on engine cleaner, mineral spirits, etc. While it's good for cleaning off grease, it will actually take the microscopic metal particles deeper into the casting. If you look at your heads they're actually fairly porous. Did I miss anything?
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Old 01-12-2006, 04:48 AM   #7
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Nope, sounds like ya got it all. Many thanks!
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Old 01-13-2006, 03:13 PM   #8
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VWHobo, you just missed telling us where we can get heads resurfaced for $30 a pair.
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Old 01-13-2006, 03:24 PM   #9
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Originally Posted by Lothar
VWHobo, you just missed telling us where we can get heads resurfaced for $30 a pair.
I'm not real familiar with the machine shops, a location description I did use, in Bellevue, WA. I suppose I could spend my time calling around, but why take all the responsibility away rom you guys.
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Old 01-13-2006, 09:44 PM   #10
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Quote:
Originally Posted by vwhobo
......

Did I miss anything?

Yes you forgot to tell him that when he tookthe heads off he probably released coolant into the pots and sump. Being corrosive he should drain the oil and wipe the bores with a lint free oily rag.
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Old 01-13-2006, 10:42 PM   #11
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head gaskets

Godlaus

Sending out the head to get resurfaced is some times a bit of overkill

Usually once the head gasket goes ther is some erosion on the head surface and the block surface. The sealing part of the head gasket is the metal ring that circles the cylinder. Erosion happens anywhere this ring makes contact.

What I've done is to clean both the block surface and heads surface well with ronsonol to remove the grease. Then take a fast drying red primer like red oxide and spray both surfaces. Let dry a few hours. Then take a brand new axe file the kind with a "beaver tail" and lightly pass over the metal sufaces with the file taking care not to gouge the sufraces. If there is any erosion then you'll see red coloured rings show up. I did a chev v6 motor that kept blowing head gaskets until I found out that the block surface had erosion on it. A couple of hours with the file cleaned it all up and it has not blown agian(been good for 2 years so far)

Vw hobo says to use feeler gages and a straight edge. This poking around will not even address the erosion problem. How do you measure erosion with feeler gages? come on get real.

Last edited by cargrime : 01-13-2006 at 10:46 PM.
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Old 01-13-2006, 11:43 PM   #12
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Quote:
Originally Posted by cargrime
Godlaus

......

I just tried to post a response to your advice and my computer seized, so I'll make a succinct response:

recommending someone who doesn't even know what lapping and milling a head is, to pick up a file and attack his block and head is very risque. Even well experienced fitters would take many hours if not days to get surfaces true.

Borebinder indents on the block should not be of concern, but if they are, a file for a few hours is not going to make much difference and I defy anyone to keep the surface true with a hand file.

Hitting an alloy head with a file is high risk for the untrained and can result in gauling with deep grooves the end result. This will especially true if the head has softened a bit from over heating. A professional mill or lap would not take as much metal off to the depth a decent scarf from a file will. Who is going to determine the hardness of the head is appropriate?

So you have draw filed you head flat with the very expensive files you bought, but how do you know it's square with the cam bearings? How much is it going to cost to remachine the bores, crankpin journals, etc after the swarf from the deck has done it's thing?

Remember that for every inaccuracy on the deck, it will compound with the inaccuracies of the head. Consider the tolerances of the rotating assembly and how deck/head mating skewing will affect them.
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Old 01-14-2006, 01:46 AM   #13
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Quote:
Originally Posted by cargrime
Godlaus

Sending out the head to get resurfaced is some times a bit of overkill

Usually once the head gasket goes ther is some erosion on the head surface and the block surface. The sealing part of the head gasket is the metal ring that circles the cylinder. Erosion happens anywhere this ring makes contact.

What I've done is to clean both the block surface and heads surface well with ronsonol to remove the grease. Then take a fast drying red primer like red oxide and spray both surfaces. Let dry a few hours. Then take a brand new axe file the kind with a "beaver tail" and lightly pass over the metal sufaces with the file taking care not to gouge the sufraces. If there is any erosion then you'll see red coloured rings show up. I did a chev v6 motor that kept blowing head gaskets until I found out that the block surface had erosion on it. A couple of hours with the file cleaned it all up and it has not blown agian(been good for 2 years so far)

Vw hobo says to use feeler gages and a straight edge. This poking around will not even address the erosion problem. How do you measure erosion with feeler gages? come on get real.
dude you're a retard
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Old 01-14-2006, 01:43 PM   #14
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Quote:
Originally Posted by cargrime
Godlaus

Sending out the head to get resurfaced is some times a bit of overkill

Usually once the head gasket goes ther is some erosion on the head surface and the block surface. The sealing part of the head gasket is the metal ring that circles the cylinder. Erosion happens anywhere this ring makes contact.

What I've done is to clean both the block surface and heads surface well with ronsonol to remove the grease. Then take a fast drying red primer like red oxide and spray both surfaces. Let dry a few hours. Then take a brand new axe file the kind with a "beaver tail" and lightly pass over the metal sufaces with the file taking care not to gouge the sufraces. If there is any erosion then you'll see red coloured rings show up. I did a chev v6 motor that kept blowing head gaskets until I found out that the block surface had erosion on it. A couple of hours with the file cleaned it all up and it has not blown agian(been good for 2 years so far)

Vw hobo says to use feeler gages and a straight edge. This poking around will not even address the erosion problem. How do you measure erosion with feeler gages? come on get real.
Gosh, why didn't I think of that. BTW, where do you get your file calibrated? People like you who give "advice" like this should be sterilized so you can't breed. Take your hammer and monkey wrench and crawl back under your rock.
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Old 01-15-2006, 12:17 AM   #15
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where do I start?

carlos and vwhobo are site roosters - just want to clear that up.

You guys have lots of book knowledge but little practical hands on experience!


Now I've hand filed my v6 block, it took actually 4 hours to do. The result was better than having the shop do it. Why do I say that?. Well some shops out there are just crap and they'll ruin your block in no time. Even the chevy factory milling machine that surfaced the block originally left milling head swirls on the block deck. it was these swirls that lead to the head gasket failure and surface erosion. So no I don't think taking out the block and risking having a shop ruin it makes any sense. Whereas a file just takes ENOUGH metal off to do the job. Ths is also quicker than pulling the engine.

Same with the head - attack them with a file! Take time when filling and get a file card to keep the file clean. Don't spend too much time filling in one spot, the movements must be smooth and continuous changing the direction of the file every now and then . Make sure you get a long file about 14''


Now another thing. Make sure you don't have cracked exhaust valve seats. These can be seen with the eye and can sometime mimick a blown head gasket. Very common on cast iron heads

vwhobo says
"
where do you get your file calibrated
"
This is a ridiculous statement
----
wally says
"
How much is it going to cost to remachine the bores, crankpin journals, etc after the swarf from the deck has done it's thing?
"

The secret is to vacuum out the cylinder bore with a shop vac to remove all fillings. Plasticene can be put in around the piston tops or tightly wadded paper towel (don't force the plasticene too hard or it'll gum up the rings) so fillings don't get into the rings Also the lifters and what not need to be masked out Fillings also get into the water jacket in the block so take a crevice tool and a peice of vinyl hose stuck in the end and you have a mini suction dredge to get the fillings and a lot of the other crap as well. Use a shop vac.
It is just common sense here but the fillings are no problem.
----

Last edited by cargrime : 01-15-2006 at 12:50 AM.
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