[schnitz]

O.K. So today I took the opportunity to pull the heads off my old '69 307. The right side head came off fairly easily, and had nothing I didn't expect to find on a 30-35,000 mile engine that's sat for the last 4 years. However, when I pulled the left side off, I found what I solidly believe to be a greyish /tan RTV sealant on the threads of all but two of the head bolts that are found under the valve cover. Two of the shorter outer bolts had the same stuff on the threads. Worse yet, one bolt has what appears to me to be a "boiled-on" anti-freeze coating on the shank between the bolt head and the threads. I'll post pics in the morning...



This was going to be a simple tear down and re-ring and bearing job , but I'm thinking this just turned ugly. And got a lot harder. The head gaskets both looked decent, and the bores all look mirror smooth, so I guess I need a bit of professional advice here. Should I proceed, or cut my losses now and just start in on the 305 that currently sits in the car?


In a while, Chet.

[ImRoyaltyInMyChevy]

so what are you exactly asking here? because on sbc's you don't need any kind of sealant on the head bolts so it wont make a difference what someone put on them.
and did you know this 307 when it was running? becasue then you would know how it ran and if anything was leaking from the head gaskets

[schnitz]

Originally Posted by ImRoyaltyInMyChevy

so what are you exactly asking here? because on sbc's you don't need any kind of sealant on the head bolts so it wont make a difference what someone put on them.
and did you know this 307 when it was running? becasue then you would know how it ran and if anything was leaking from the head gaskets

I'm asking (primarily) if it's a strange thing to find RTV on the threads to head bolts on a low fairly low mileage engine. I bought this engine over ten years ago, and it's sat waiting for a rebuild for the last number of years. I pulled it when the cylinders would no longer hold any compression (the best was 70psi--and the best with oil over the rings was around 83 IIRC...). I had ran it intermittently for the first years I had it, using it as a "back-up" for a number of vehicles I owned. It ran fine once started, just had low compression, and it would need a few extra cranks to fire up. Sorry for not being clearer, hopefully I did better this time around. Thanks,


In a while, Chet.

[ImRoyaltyInMyChevy]

well I don't think that is anything to worry about, the only way that it could've gotten there though is from a pretty lousy mechanic who put the engine together last. But that is something to worry about, because who knows what other mistakes he made on the engine that you will find over time.

[schnitz]

Oh boy. I had pulled this from an almost 25,000 mile '69 C10 pick-up. It was frame rotted so badly it had to be loaded in multiple pieces. Wouldn't one think that a lower mileage engine wouldn't have ever needed to be that far apart. Makes me wonder what else I'll find....


In a while, Chet.

[ImRoyaltyInMyChevy]

oops I messed up when I said that head bolts don't need any sealant, they definitely do, but not RTV lol my bad

and well you can never judge an engine by the mileage. theres definitely some better running 250,xxx miles engines out there then some 50,xxx mile engines. just depends how it was treated and maintained. and also on whose working on it and why.
for instance my dad bought a 78 chevy 3/4 with 55,xxx miles, but what do'ya know, it's a sledge monster and I killed the engine from alot of highway driving .
it was the original old man who owned it, but what happened was he only really drove the truck to work and his work was so close to home the engine never got wormed enough to keep it flowing good and clean.

[65smallblock]

I would be more concerned if the threads were NOT sealed. The bolt holes go directly into the water jackets.. There are several different kinds of thread sealer that work just fine.

[sbchevfreak]

I'd just clean them off, tap the holes in the block, and put a brush on teflon sealant on the threads when you put the bolts back in.

[DoubleVision]

Man chet, I`ve used RTV sealant on more head bolts than I can count, still do so to this day. clean the bolts, and when you reuse them if they don`t feel spoungy they are fine.

[schnitz]

I thought you were supposed to avoid using anything on head bolts because it would mess up the torque settings. Was I wrong?

In a while, Chet.

[ericnova72]

Nope, they go into the water jacket, you've got to seal them somehow or you will have a leaker.

[DoubleVision]

From past experience when I seen others that didn`t use anything, coolant would make it`s way up the bolts into the heads.

[Stroke]

I`ve used RTV sealant on more head bolts than I can count, still do so to this day. clean the bolts, and when you reuse them if they don`t feel spoungy they are fine

I can honestly say I don't have any real use for RTV. I would never use it on a head bolt, or stud What the heck would be feeling spongy??? The old silicone still on the threads when torquing?

IMHO, there are products better suited for the task than RTV - which is always found somewhere it does not belong. I have found tubs of it over the years, in sump pick-ups, radiators, thermostats, oil galleys, orifices, in the lifter valley, used on intakes as well as throughout the crankcases of various engines, transmission pans/filters, and rear ends. It is not compatible with everything. I have even seen it on lug nuts!!! I hate RTV The 'a little is good a lot is better' mentality seems to be the case with this stuff. Permatex #2 or #80019 for me. JMO

Thank You very much.

the only way that it could've gotten there though is from a pretty lousy mechanic who put the engine together last. But that is something to worry about, because who knows what other mistakes he made on the engine that you will find over time

Thank You x 2

[DoubleVision]

I take it you never broke a head bolt? or any bolt? they feel like a spounge when they are about to break. I only use RTV when and where it`s needed and rather sparingly, to this day I haven`t had any issues. To each of his own, your welcome very much.

[matt167]

When I rebuilt my Ford 200 I6. 2 of the head bolts go into oil galleys. the Motors manual I had said to use RTV sealent on those 2 bolts... to even everything up, I used RTV sealent on all the bolts...

Also, when I had to remove the gas filler neck from my Falcon to weld in a return connection, the gasket got destroyed.. I ran a bead of RTV, let it dry, then bolted it all up. sealed perfectly.