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View Full Version : Heat Riser Exhaust Valve - Repeal or Replace?


del
07-15-2017, 11:22 AM
Greetings All - Hope you are enjoying summer here in the northern hemisphere!

My 1960 352 heat riser is stuck. Looks like compared to the drawing in the shop manual it's at least partially open... From what I'm reading here, looks like many 352 owners eliminate the valve or disable it, so for about 1/3 of the cost of a replacement valve, is there any reason why I should not just go with the 390 spacer and be done with it? I think I've only used the heater 2x in 8 years so that's not an issue.

Thanks,

Joe Johnston
07-15-2017, 11:43 AM
Not needing a faster warm up, or heater, I would go with a spacer. BUT FIRST, I would use a good penetrating oil on both sides to try and free it up over a couple of days. Oil and a couple of raps with a hammer may be all you need. Once open, a bit of wire will keep it that way. My method may be crude, but easier than fighting rusty exhaust nuts and studs.

del
07-15-2017, 12:23 PM
Thanks Joe I have WD40 which is probably not adequate for this. What would you use? I agree 100% re fighting the bolts. I see that the shop manual calls for removing the exhaust manifold to replace the valve. Is that necessary??

Joe Johnston
07-15-2017, 12:49 PM
BP Blaster or Kroil (if you can find it) are excellent products and similar products are available at any auto parts store.

WD40 is not as good as penetrating oil.

Never tried it but it might work great in this application is to hold a candle against the hot threads or pivots of the heat riser. Supposed to wick into the voids and quickly penetrate and loosen frozen parts. Always wanted to try it, but I grab
a spray can of PB Blaster before thinking of it.

I definitely would do all I could without removing the exhaust manifold.

Ladysmith Bob
07-15-2017, 01:25 PM
If you decide to remove heat riser getting nuts off of studs is not too bad. You need to heat stud nuts cherry red then quench with lots of water right away. By doing it this way the nuts will cool and shrink while on the studs, then the studs will cool and shrink off of the nuts. Hope this helps if you need to go that far.

simplyconnected
07-15-2017, 06:01 PM
Who drives their classic in winter? If I start my engine in winter months I want it to run for awhile.

For these reasons I blocked off the exhaust crossover in the intake manifold and 'gutted' my heat riser valve. At the time, I was assembling the engine.

I simply cut the middle out of the heat riser with a torch. The outsides still look the same (although they cannot move). Of course, there is a 'blank spacer' for sale but I simply made my own from the original piece. The insides are smooth with no holes. No restriction, no exhaust escape.

I have heard from many dozens of owners who knew their gas mileage was bad, power wasn't quite there and they had terrible heat problems. Yep, all due to a stuck-shut heat riser valve. A few used a small hammer to knock the valve open. They simply hit their stuck valve until it rotated into the open position, then left it that way.

BTW, Bulldozer engines, 430 MELs, never used a heat riser valve. - Dave

del
07-16-2017, 12:53 PM
PB Blaster has worked it's magic! A couple of good shots yesterday, and earlier this morning a couple of raps with a small hammer got it to move. More PB and a couple hours later, more taps and it is full open. Haven't wired it open yet, but for now it's stuck open. I'm gonna keep my eye on it and see what happens when the engine cools down. Took it for a 15 mile spin to burn off the PB, stop and go & highway, and gauge reflects reduced running TEMP! Thanks for the help gents!

Joe Johnston
07-16-2017, 01:44 PM
that is what we want. quick, easy, inexpensive, no broken bolts or skinned knuckles!!

jopizz
07-16-2017, 03:50 PM
Usually after you free them up they start leaking from around the shaft. Not a big deal but just be aware in case you hear an exhaust leak and can't figure out where it's coming from.

John