3.8 cylinder heads and head gasket

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3.8 cylinder heads and head gasket

January 05, 2011, 03:16:00 PM

hi guys

what are some thoughts on replacing the cylinder heads on a 1984 3.8 6 cylinder. im going to have to do the head gakets. i put some steel seal head gasket repair stuff in back sometime ago and it held up for awhile but now im having problems again. the car isnt blowing it out the back , but out of the radiator . sometimes the back pressure sounds like a tea kettle. any way whats the thoughts on replacing the heads too, just to be sure . i saw a link on eric's cool cats for a place in florida for brand new ones .
i kinda dont want to do this and pay someone , but i know its going be big bucks. i did do head gaskets on my 1989 continental and i guess if i did that one , this one has to be way easier.
thanks
eddie

3.8 cylinder heads and head gasket

Reply #1 – January 05, 2011, 03:22:24 PM

I would'nt get new heads. I worked at a machine shop for about five years and I've only seen a 3.8 head crack once, it was a carbed head. I would just have the heads that you have pressure checked and milled. They're a most likely fine.

3.8 cylinder heads and head gasket

Reply #2 – January 05, 2011, 03:42:00 PM

Just throwing info into the hat for the sake of argument...

The Clearwater Cylinder Heads on my '84 were brand new castings (I believe made in Mexico) and were fully assembled. They tested perfectly flat with a straight edge. There were absolutely no issues with them whatsoever and that's why I recommended them on the site.

My old heads ended up being cracked. There were hairline cracks that would have shown up had we gotten the heads Magnafluxed, but there wasn't a lot of time for a trip to the machine shop. We didn't know about the cracks until the head gaskets were replaced and everything was put back together...fired up the engine and water just poured out both sides of the motor just like a faucet. At that point I was sure glad that we didn't have the heads machined flat!

Sometimes you get lucky with a 3.8 head, sometimes you don't. After a rather slim selection at local salvage yards, I opted to try the CCH head and was extremely happy that I did. For the money it was the best solution for me.

Now...if you have access to a local machine shop and they can test them for you, that would be a good place to start. You'll know real soon whether or not to keep the existing heads. IF you need new ones, CCH is the way to go. IF not, you're all set.

3.8 cylinder heads and head gasket

Reply #3 – January 05, 2011, 04:02:54 PM

And for what it's worth, I have a set of '88 3.8 heads that ARE good. The reason the engine is bad was a thrown rod. I'll have them tested even..someone may as well use them..I never will.

3.8 cylinder heads and head gasket

Reply #4 – January 05, 2011, 06:54:40 PM

Quote from: ThunderbirdSport302;348487

And for what it's worth, I have a set of '88 3.8 heads that ARE good. The reason the engine is bad was a thrown rod. I'll have them tested even..someone may as well use them..I never will.

incase you were asking him, your 88 efi heads wont work on his 84 cfi motor.

3.8 cylinder heads and head gasket

Reply #5 – January 05, 2011, 07:55:11 PM

Quote from: Ductape91;348497

incase you were asking him, your 88 efi heads wont work on his 84 cfi motor.

I was about to say the same thing

3.8 cylinder heads and head gasket

Reply #6 – January 06, 2011, 05:40:26 PM

2 more questions on this .... are there any heads available that will give this y 3.8 a little more power and if so would you even notice it? and is it possible to replace the aluminum heads with cast iron ??

thanks
eddie

3.8 cylinder heads and head gasket

Reply #7 – January 06, 2011, 06:31:11 PM

They dont make cast iron heads for the 3.8.

3.8 cylinder heads and head gasket

Reply #8 – January 06, 2011, 06:55:08 PM

Really with the CFI engine you are not going to get much more power out of it in that configuration. Also the cylinder heads tend to corrode around the water passage openings making them junk unless the machine shop will weld in new material and level it. If the machine shop finds that they are good you should keep the heads you have. It will save you money. The odds are that the valves are still good along with the guides and you'll only need seals and resurfacing if necessary.

I think over the years there were about 8-10 3.8 configurations, some with balance shafts, some without and various head and intake manifold configurations. I don't have a whole lot of experience with the different configurations but I understand the 91 and up Mustang 3.8s were real good. But then you'll have a lot of wiring issues if you were to install one of the Mustang EFI engines.

3.8 cylinder heads and head gasket

Reply #9 – January 06, 2011, 08:11:46 PM

actually you're best bet is to just swap in a 88 engine if you're bent on keeping a 3.8. The wiring isn't actually that different and its definitely more powerful than the 87 and back. But, you can built a good strong and descently fast CFI. A few people here have done it.

3.8 cylinder heads and head gasket

Reply #10 – January 08, 2011, 01:04:52 AM

or a simple top end swap. same eec should / will work fine imho. the rest is rather one step at at time like TB linkage, IAC connector and vac line routing.

3.8 cylinder heads and head gasket

Reply #11 – January 08, 2011, 09:34:48 AM

you cant swap 87/88 top end. The blocks are different. 88 heads are longer b/c of the balance shaft in the 88 block.

3.8 cylinder heads and head gasket

Reply #12 – January 08, 2011, 10:47:36 PM

thanks for the info ... i think im going go for new heads, i will decide when i get this apart.
does anyone have a write up or tips on how to do it? i think i can do it with , just taking it apart.
besides replacing the head gasket , i guess i shoulf replace to cfi gasket too and the exhaust intake too. about how long could this take to do ?

thanks
eddie

3.8 cylinder heads and head gasket

Reply #13 – January 09, 2011, 12:52:54 PM

Quote from: sarjxxx;348845

you cant swap 87/88 top end. The blocks are different. 88 heads are longer b/c of the balance shaft in the 88 block.

thats news to me and a lot of other people. what your saying is the 88 3.8 heads do not fit on the 87 and down blocks. the balance shaft has nothing to do with the heads.

Quote from: blackcat85;348845

thanks for the info ... i think im going go for new heads, i will decide when i get this apart.
does anyone have a write up or tips on how to do it? i think i can do it with , just taking it apart.
besides replacing the head gasket , i guess i shoulf replace to cfi gasket too and the exhaust intake too. about how long could this take to do ?.

click on my diy link below.
lots of cfi stuff in there.
you should buy the 3.8 head gasket kit which will come with all the gaskets you need for the top end.
You need to buy the CFI base plate gasket kit separate, adance has always sourced the best kit for this imho, ive done 3.

3.8 cylinder heads and head gasket

Reply #14 – January 09, 2011, 01:10:23 PM

I will add that you will need to torque the heads down exactly as the book says, to stretch the bolts correctly... and you need new head bolts. You can't reuse them on a 3.8.