Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: dw85745 on February 26, 2012, 05:47:19 PM

Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on February 26, 2012, 05:47:19 PM
Am &*^%$#.  Found a small head gasket leak on the drivers side.
(Haystack -- I guess you were right!!!!)

My guess is that it was leaking previously but the engine was burning off the coolant
so leak was not obvious.  Since engine was re-built less than 5000 miles ago
any chance:

!)  I can get away with just re-tightening the head bolts??
2)  If so, my guess is I should loosen -- each one individually, say by two complete turns, and then retorque. 
3)  How about the short ones that need sealant?  Should these be pulled (removed) completely and then checked for sealant or new sealant added  or just do a two turn backoff ?



David
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: daminc on February 26, 2012, 06:04:43 PM
you can not re-torque or re-use headbolts on a 3.8.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Shadow on February 26, 2012, 06:15:19 PM
if you remove any head bolts, you might as well pull the head and replace the gasket.. removing or loosening any head bolts will compromise the gasket and will be pr0ne to leak even worse.. and as jerry said, the head bolts aren't reusable.. they're 'torque to yield'
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Beau on February 26, 2012, 07:16:49 PM
Exactly...do 'er right the first time, save yourself trouble in the long, or would that be a short run lol.

If the engine has gotten hot, might want to have the heads surfaced by a GOOD shop....also there's a better head gasket to use, but can't think of which brand it is right now. Someone more intimate with 3.8s will chime in though.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Bruce M on February 26, 2012, 07:23:50 PM
Fel-Pro.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: TOM Renzo on February 26, 2012, 08:17:47 PM
Ford has an up dated gasket. The Bolts are TTY and cant be reused. Pull the head something is wrong!!!

Those engines are known to eat head gaskets.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on February 26, 2012, 09:13:05 PM
The reason I raise the issue is based on the NOTE in the shop manual:

Quote

CAJTION: Always use new cylinder head bolts
to assure a leak-tight assembly. Torque
retention with used bolts can vary, which may
result in coolant or compression leakage at the
cylinder head mating surface area.
Tighiten the cylinder head attaching bolts in
sequence as follows:
50 N-m (37 Ib-ft)
60 N-m (45 Ib-ft)
70 N-m (52 Ib-ft)
80 N-m (59 Ib-ft)
Back-off the attaching bolts 2-3 turns.
Repeat Steps a-d.

NOTE: When cylinder head attaching bolts have
been tightened using the above procedure, it is not
neessary to retighten the bolts after extended
engine operation. However, the bolts can be..........<<{THIS IS WHAT I AM REFERRING TO}
checked for tightness if desired.

Nothing is said about if they are not to torque when checked.
Seems klnda ridiculous that you would need to do a new head job if the bolts are loose.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Beau on February 26, 2012, 09:24:00 PM
Sure, just torque 'em down to about 100 lb-ft each and call it a day.


Trust me...this ain't something you wanna cheap out on. BT, DT.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: XR7 on February 26, 2012, 10:57:33 PM
who rebuilt the engine 5000 miles ago?
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Shadow on February 27, 2012, 12:46:43 AM
cover your as*.. get ARP bolts, new gaskets and have the heads checked by a machine shop.. i wouldn't recommend going back to the guy who rebuilt the motor, as i remember reading the fiasco with the motor you had before.. using ARP bolts will pay for themselves, as they're reusable and much better quality (times a million!)
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on February 27, 2012, 08:24:36 AM
Thanks all for input. 

Quote
i wouldn't recommend going back to the guy who rebuilt the motor,

I agree.  Same engine.  "Supposedly" did the head bolts twice (drivers side) as I took it back after about 1500 with a leak (drivers side).
Wondering if a new head may help, or if the old Cougar has just reached the end of its life cycle? 

Shadow -- will check into ARP bolts.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Beau on February 27, 2012, 11:43:16 AM
Quote from: dw85745;382130
Wondering if a new head may help, or if the old Cougar has just reached the end of its life cycle?

No sense in junking the car over a leaky head gasket and  bolts. If you love the car and have time and $ to fix it.....
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on February 27, 2012, 05:04:22 PM
Quote
No sense in junking the car over a leaky head gasket and  bolts. If you love the car and have time and $ to fix it.....

Agree.  That's why thinking of doing it myself this time.  Plan to go with ARP studs.
However, sometimes you reach a point in life where the hassle is not worth it.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on February 29, 2012, 10:42:46 PM
Question for anyone who has done a 3.8L manifold or head gasket:

1)  Based on the Tech info I am able to gain access to, a number of people reported that 1984 3.8L coolant leaks emanate from the intake manifold to cylinder head joint rather than the head gasket.
This doesn't appear (from my looking) to be my situation, as the leak seems to be coming from around the center of the head gasket looking up from underneath the vehicle.
Anyone else had leaks around this area?

2)  Has anyone tried just retorquing the head bolts to see if it solves the problem? If so, any issues and did it work?

3)  Has anyone tried to replace the head bolts with studs.  If so, what procedure did you use??
a)  Drain cooling system and engine oil
b)  To keep from removing the intake and the cylinder, did anyone try
......-- unloosing all bolts in the reverse in which they were torqued -- maybe two to three turns --
then remove each bolt individually and replace with studs
-- or --
.......--  Completely remove each bolt one at a time and replace with a stud?
-- or  -- Whatever other procedure
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Shadow on February 29, 2012, 11:29:22 PM
removing any head bolts will compromise the gasket.. if it's leaking, just pull it apart and fix it the right way.. no point in half-assing it.. no offense
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on March 01, 2012, 03:31:14 PM
Quote
no point in half-assing it.. no offense

No I get it.  Just curious if someone found a simpler solution as to do the head the intake has to come off and "maybe" the front timing cover (need to check this) because of the intake removal.
On the 3.8L, I know the oil pan needs to be removed to get at the front timing cover.  So we're talking MAJOR effort here if the timing cover has to be removed just to do a head gasket.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: sarjxxx on March 01, 2012, 11:15:12 PM
Quote from: dw85745;382624
No I get it.  Just curious if someone found a simpler solution as to do the head the intake has to come off and "maybe" the front timing cover (need to check this) because of the intake removal.
On the 3.8L, I know the oil pan needs to be removed to get at the front timing cover.  So we're talking MAJOR effort here if the timing cover has to be removed just to do a head gasket.

Unless the 84 3.8 is drastically different from the 88 3.8 you don't actually have to remove the oil pan to take off the timing cover, just take the 2 bolts out from the oil pan to the bottom of the timing cover. Mine came off no problem. Although, I'm 95% sure you don't have to remove it to do heads anyway. But if you do, make sure you don't forget about the allen head bolt that goes through on the bottom right corner, behind the oil filter. That one is easy to miss and I broke the corner of my timing cover off because of that bolt not being out.
Quote from: dw85745;382576
Question for anyone who has done a 3.8L manifold or head gasket:

1)  Based on the Tech info I am able to gain access to, a number of people reported that 1984 3.8L coolant leaks emanate from the intake manifold to cylinder head joint rather than the head gasket.
This doesn't appear (from my looking) to be my situation, as the leak seems to be coming from around the center of the head gasket looking up from underneath the vehicle.
Anyone else had leaks around this area?

Yes, that wouldn't surprise me if you had a leak there. The heads have water jackets on both the front and back ends and the but the back end has nowhere to go. At least that is the way it is with 88-98 intakes. Yours may be different, I think the reason the passageways are still there on EFI heads is because of the fact that the carb and CFI intakes had a passageway for it to run through. However, if not, and the intake is the same, then it would not surprise me, because I did have a leak there myself, on 2 year old gaskets even. Only difference being that mine was leaking into my intake runners instead of out the top of the engine.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on March 02, 2012, 11:37:59 AM
sarjxxx:

Thanks for the input.  BTW, checked and timing cover does NOT need to come off.
 
Only one small leak (more of a weep than a leak), and nothing in the oil I can see.
Putting a pressure tester on the cooling system, shows NO leakdown of pressure.
Vehicle runs great and manifold vacuum is rock steady and right  at 19 1/2  Hg,

I  may be hard headed -- or -- hope springs eternal -- but thought I'd give it a shot by just replacing the head bolts with studs
without removing them.  I know this goes against the recommendation of most here (this forum).
I figure high probability may work, so nothing lost, and if does not work can always go the other route.

Only issue I'm having is after draining the cooling and engine oil, whether to:
1)  replace one bolt at a time (leaving the others tight in place), or
2)  whether to loosen all the bolts in reverse torque order until stress removed, and then replace each one with studs. 

With the first figured I'd go with the install torque bolt order and torque each to spec as installing.
With the second, it would be like a normal head install,  with the bolts only keeping the head positioned while replacing the bolts.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: Shadow on March 02, 2012, 12:22:21 PM
well.. if you're going to do it that way, than untorque all bolts at the same time.. taking 1 out may cause you an even bigger headache
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: sarjxxx on March 02, 2012, 06:36:55 PM
Quote from: Shadow;382727
well.. if you're going to do it that way, than untorque all bolts at the same time.. taking 1 out may cause you an even bigger headache

:iagree:
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: dw85745 on March 04, 2012, 07:27:39 PM
Shadow and sarjxxx:

Appreciate the feedback.    Increased the comfort zone to this approach.
Title: Head Gasket bolts -- tighten or replace (1984, 3.8L)
Post by: sarjxxx on March 04, 2012, 07:31:54 PM
Although, I'm not sure why you don't just pull the intakes off... they're not that hard to get off, not to mention it would give you chance to change that intake/head gasket just for safe measure, and I'm pretty sure the lower is bolted to the heads anyway so if you don't unbolt it you may not get the proper torque off when you reinstall the new bolts/studs.