Freeze plug question

35th T-bird SC

Registered User
I have this kit for 1990 3.8L and the plugs that go in the oil gallery under the timing cover won't thread in. It's like its a different thread per inch. My originals are lost somewhere at the machine shop and the ones the shop gave me are the same as the kit. 18 threads per inch. Also the freeze plug that goes in the valley of the engine above the lifters in the back is wrong. The kit gave me one 2 1/4" deep that I put over the cam and Two 2 3 /16" shallow that doesn't fit tight at the top. Also I can't remember was there one at the front hole at the timing cover going into the valley area?
 
Did you take pictures before you took the engine apart?



I put my own plugs in. The plug for the counterbalance shaft used on front wheel drive was not taken out of mine. Is that the one you say is wrong?


Also I used the oil galley plugs in my kit and they worked fine. Have you chased the threads to clean them up? You may have corrosion and old sealer gumming the threads.
 
Is that what that vacant spot for a shaft is for? Never knew that it was for a counterbalznce shaft. I know the one back by the flywheel enf had a plug but I can't remember if the one by the timing cover did. And the 2 3/16 plugs fit loosely in those holes.
 
Yes thats where a counterbalance shaft is on some 3.8's.
The back hole gets a freeze plug in it the front hole behind the timing cover get NO plug at all.
The oil galley plugs are a national pipe thread so the plugs will screw in tight after the first couple of initial turns, they dont just screw in easy and then bottom out like a bolt does. I recomend you put Teflon pipe thread paste on those threads before you install them. A leak on one of those plugs will reduce the amount of oil that will travel to those lifters and cam journals.
 
Last edited:
I did'nt install my freeze plugs, my machinist did so I dont know what size they are. I do know that some of the plugs that came with the plug pack were not used on this engine, apparentaly there packaged to service any 3.8 engine. The permatex is fine for sealing those, ut has tremendous holding power once it sets up and actually may hold the freeze plug in when it needs to blow out and protect the block. Permatex Aviation gasket sealer was used on my plugs and is the choice of my machinist.
 
I'm still having problems with these front oil gallery plugs. I tapped the threads and a 5/8 x 18 tap went right in but the same size plugs will not go in no matter what. It's almost like the plugs I have are too fat at the first threads to get started. I got one started and it got tight after about one revolution and wouldn't go in. What plug do I need?
 
Sounds like the threads are not the same, its been so long since I put those in I dont remember if there metric or standard thread.
I just reused the galley plugs so I had no problems with that.
Be careful chasing those threads with a tap. You must use a NPT(National Pipe Thread) tap. Pipe threads are tapered and they tighten up as the plug is screwed in, a regular bolt thread tap will make the threads straight and the will not tighten up on the plug and oil will leak past the threads.
You can get a thread pitch gauge from Sears or most places that sell tools. There not expensive and come in very handy at times.
The gauge looks like a feeler gauge set except the edges of the blades have teeth cut in them. You test fit those teeth into the threads until you find the ones that fit you threads.
 
The threads on my plugs intertwined perfectly with the threads on my tap so it is 5/8" x18. I'm stumped because the tap went in real nice but these plugs will not start. I've got to figure something out. I went over to pep boys but they took down all their hardware boxes I was gonna look for a plug with more of a taper but same diameter and pitch.
 
Check with a Ford parts man because he can look them up and it will tell him what size and thread pitch they are. Have him look up the "Front lifter galley plugs".
 
Back
Top