Frogger2662 Posted June 10, 2021 Share Posted June 10, 2021 Starting to put my 5.0 back together this weekend. What do ya'll use on the lower head bolts to seal them from the coolant? Thanks Link to comment Share on other sites More sharing options...
Rembrant Posted June 10, 2021 Share Posted June 10, 2021 The engine shop that built my 1984 302 used an ARP thread sealant (white stuff). The same or similar to Permatex high temp thread sealant afaik. My '84 302 was the same...the lower head bolt holes went right through into the coolant jacket. That change apparently happened early in the 1980's, and the previous blocks had blind holes for the head bolts. Some internet experts argue that the through holes only showed up on the roller block castings starting in 1985, but my flat tappet '84 302 had through holes. Link to comment Share on other sites More sharing options...
Frogger2662 Posted June 10, 2021 Author Share Posted June 10, 2021 The engine shop that built my 1984 302 used an ARP thread sealant (white stuff). The same or similar to Permatex high temp thread sealant afaik. My '84 302 was the same...the lower head bolt holes went right through into the coolant jacket. That change apparently happened early in the 1980's, and the previous blocks had blind holes for the head bolts. Some internet experts argue that the through holes only showed up on the roller block castings starting in 1985, but my flat tappet '84 302 had through holes. Thanks. My block is a later 92 roller block. Link to comment Share on other sites More sharing options...
Rusty_S85 Posted June 11, 2021 Share Posted June 11, 2021 Starting to put my 5.0 back together this weekend. What do ya'll use on the lower head bolts to seal them from the coolant? Thanks ARP Thread sealer, its similar to pipe dope that you just spread on the threads and install it. I was turned onto this when I started working at my current job years ago. Never seen a leak with it and I have a tube of the ARP thread sealer as well as a small tube of the ARP lube for between the bolt head and washer and on the threads of the blind head bolts. What ever you do, dont use silicone or RTV. A gm I6 I had to pull the head off at work on a mint '72 C10 that was gone through not only did they used horrible valve guides that failed in under 10k miles they also used red rtv on all the head bolts and they were no where near the 95 ft-lb torque they should have been. That rtv/silicone really screws with the torque reading especially if it starts to set up on you during the torq senquence. The thread sealer never hardens or dries out so you wont have that issue. Link to comment Share on other sites More sharing options...
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