View Full Version : TR2/3/3A Paging TR3driver re blocked bypass and Shaller pdf

04-21-2012, 01:38 PM
I was looking at an old post about blocking the bypass on a TR4 . When you read the write up by Bob Shaller in his More BS on TR3's he makes an argument for blocking the bypass ,when not using a sleeved thermostat,so more coolant would circulate and he was down in Arizona where the temperatures would be quite high. You mentioned in an old post that you would not recommend this as it may increase the likelihood of a cracked head.(I believe TR4's were being discussed in that post though and not TR3's). I've been running a blocked bypass for years now in my TR3 with no issues but recently talked to someone (who has more of a hot rod background) that said he dosn't recommend blocking the bypass either because it could cause hot spots in the head on a TR3? Now I'm getting a little paranoid about leaving the plug in. So why did it seem to work for Shaller down in Arizona? What's the correct take on bypass blocking for a TR3?

04-21-2012, 02:45 PM
Hard to say what is "correct", when you're talking about opinions. I stick by mine, which is that having no water circulation at all is playing with fire.

OTOH, TR3/4 heads most often crack where it goes unnoticed, in the web between #2 and #3 (which has water on both sides so the crack doesn't really hurt anything).

If you lived out in the desert, I could see an argument for blocking the bypass and instead drilling a hole through the thermostat (so that some water circulates through the radiator even with the thermostat closed). But I'm thinking you might not like the slower warm-ups in Winnipeg.

I do drive out into the desert on occasion; and my experience had been that, with a radiator in good condition and the bypass open; the driver overheats long before the engine does. For example, driving in traffic in downtown Palm Springs a few years back, it was around 115F in the shade and the TR was staying under 200F. But my wife and I got so hot that we stopped at a Motel 6 just to cool off in the air conditioned room.

I have also experimented with blocking the bypass on several occasions, when I was having cooling problems, and it has never made enough difference to even notice. It may be that there is some condition where it would make a difference, but I haven't found it yet.

But these are just my opinions and experiences. Others may well have different ones, just as valid. Ultimately, you have to decide what you want to do.

PS, just in case anyone is wondering, I have a lot of respect for Bob Schaller. He was a gentleman and a true asset to the hobby. I just don't always agree with him :smile: