B-Man

Update: I finally got the rear wheels installed this morning and the MC out of the garage. I went with another pair of the Cooper Cobras on the rear, same as the front

Update: I drove my MC to work this morning WITHOUT a thermostat installed, and only water in as coolant. It ran just under 150F the entire time at about 45mph and 2000rpm. I will drive it around a bit more over the next couple of days. This weekend I will put the 180F thermostat in, some 50/50, and replace the upper and lower hoses. Then I will daily it next week. Hopefully the cooling issue will be solved. Of course, New England fall temps are setting in, so that will make it easier :). Enjoy the ride folks!

@420ponies, thanks for the reminder on drilling a hole. I had completely forgotten about that. Great call. 160 vs 180 ... hmmm, something to think about. Might play around with both and prove you right or wrong!!! @Scott S. oh man, you're right! I should pour some down in there - some for the gods of cooling!!! But no, it does not have an aftermarket transmission cooler. I confirmed yesterday that the transmission cooling lines are threaded into the passenger side of the radiator, presumably in stock form.

Update on the cooling system inspection: I'm not going to make a separate thread. I don't think this forum needs another dedicated thread on such a simple system. Anyway, - when I pulled the radiator cap off, I could see coolant about halfway down the radiator. So a little low for sure. I know I've filled and burped the system before but it was at least a season ago. - I pulled the lower radiator hose and drained all of the coolant into a bucket - I removed the thermostat housing and discovered that there IS in fact a thermostat in there (yay). It's a 160F unit, which was a bit surprising. - I pulled the thermostat out, replaced the housing / rubber oring gasket, disconnected the upper radiator hose at the radiator and flushed the cooling system. I put the hose into the radiator and let the upper radiator hose spew fresh water onto the ground. I let it run for a while like that for a while, with a few high RPM revs to churn things up - the water looked very clear with absolutely zero signs of corrosion in the system (yay). And the water pump seemed to be pushing an expected volume of water, and increased with RPM. - the upper radiator hose ended up laying against the AC belt / pulley and now needs to be replaced (bummer) - I filled and burped the system with fresh water (no antifreeze) and left the thermostat out. - I took the car for a rip around town and it never got over 180F So no smoking gun here relative to my intermittent high temp issues. I can't imagine the 160F thermostat was doing all that, but I might be mistaken. The coolant being a little low ... maybe My plan from here is to go ahead and put the 180F thermostat in, leave the 100% water for now, fill and burp it, and run it to see if the issue reoccurs. If it doesn't then I will drain the system of straight water, refill with 50/50 coolant and call it a day

@Rob Petersand @Scott S. I actually don't even know if there is a thermostat even installed to be honest. I bought one, and all of the associated essentials, from an O'Reilly's when I went on the first 2+ hour road trip earlier this summer and saw the temp creep up past 210F. It's still on the shelf. But yeah, one of the first things I will check. While the water pump isn't making any noise, I do question whether it's functioning optimally. Could be anything at this point I suppose. Given how bad the front (and rear) main seal leaks I may be in for a might-as-well strip the whole front of the engine down. We shall see. First things first though is a good coolant system flush, check flow (water pump) and see if a thermostat is in play.

Summer of 2025 update - it's been a while! Well, my MC has been sitting back in the garage since I think mid-June. Ugh, how the heck does this happen???!!!???! I've been having a great summer in general and I let some cooling system issues cause me to relegate the car to the garage. Only because I havent made time to address them. And one of the tires went flat due to age and a sidewall crack. So new tires have been in process (see my Suspension Upgrade thread). Well, it's a cool morning here in New England and I figured I'd drive it to work this morning. I made it a few miles before the temp gauge made it upwards of 240F - dang it! I turned around and it did cool down some. I made it home, tucked it back in the garage and took my 78 Triumph Spitfire to work instead. Expect a 'cooling system rebuild' thread in my near future. Hopefully it's a quick one that will get me back on the road for some New England fall road trips. We shall see!

Ok, after more research it sounds like the 275/60-15 tire size is too wide for the 7in wide stock wheels that I have. I really dont feel like sourcing and buying some 8in wide wheels. I'm just going to order up 2 more 255/60-15 Cooper Cobras and get the dang car back on the road!!

It looks like the 275/60-15 is the right balance without pushing too much into that 3/4 in clearance (I think another forum member said this earlier in the thread). This will be 0.8in wider and 1.0 taller than the 255/60-15. So 0.4 of the 0.75 clearance will be eaten up. Fingers crossed, not a big deal

Ok I FINALLY had a chance to swap the 255/60-15 tires on the driver side from front to rear for a fit check. Here are the resulting clearance measurements (inch) 2 1/4 front of tire to trim 4 1/4 rear of tire to trim 3 1/4 down from horizontal fender edge to sidewall tangent 3/4 tangent sidewall to fender edge extended down with a straight edge (see photo). This is the dimension that will close with wider tires and the suspension flexing down or in a corner. 2 frame front, inside sidewall 2 1/4 frame rear, inside sidewall I might see about a tire up to 1 inch wider, but wouldn't go more than that without rolling the lip of the fender

From above, "Caveat - my front suspension is still 100% original and well worn, other than the Bilstein shocks I put in (see earlier in this thread)"

I got the 255/60-15 Cooper Cobras on the front of my 72 yesterday, and took her for a rip this morning. As expected, zero issues with them in the front. Even with sharp, hard cornering. Caveat - my front suspension is still 100% original and well worn, other than the Bilstein shocks I put in (see earlier in this thread) In this photo I measure: Floor to trim 27 1/2 in Front of tire to fender trim 1 1/2 in Rear of tire to fender trim 4 1/2 in When the wheels are turned all the way to the left, there is about 1 1/2 in (est) between the rear, inside wall of the tire and the control arm. When the wheels are turned all the way to the right, there is about 3 1/2 in (est) between the forward, inside wall of the tire and the away bar. I'm definitely going to bigger in the rear. Will have to go back in this thread, the wheel / tire thread and elsewhere to take my best, safe guesstimate. But thanks for the help here everyone!

Holy heck, you should encourage the Rust Replace guys to add this part and instruction to their rear window rebuild kit! Would have been good to implement when I did all that to my 72

@Jackaroo, I just a few minutes ago posted in my suspension upgrade thread. I have a few photos of my 72 front suspension (unmolested) in there, which may prove useful to you?

Update on the tire purchase ... the other day I bought Qty2 of the Copper Cobra 255/60-15 tires off of Amazon for $158 each off of Amazon (free shipping of course), and its a 7-day lead time (coming in on Monday 7/28). I figured I would buy 2 to start and replace just the fronts. My concern is that the 255/60-15s might be at the peak of what can fit up front, but will fit just fine in the rear. If I can drive around for a bit with them on the front and confirm that for my MC there are no unintended consequences, then I will leave them and order 2 more for the rear. Else, I will move them to the rear and get something a bit smaller for the front (whatever I'm currently running, would have to go back through this thread). Anyway, thats the tire plan update @Robnhood, yep that's ye ol faithful Nautilus in the background. Certainly a relic now, but one of the coolest of the coolest no doubt! I live nearby and make it over there at least once a year for one reason or another. My dad (retired sub Captain [Sturgeon -class]) was on the board at the museum forever. And I work, sort of, in the industry.

Well I went out to the garage this morning, and the front left tire was flat again. So i guess the dry rot in the tires is a terminal issue. And yes, I got VERY lucky that it happened while in my AC'd garage, right next to my tools and jack stands, and NOT on the highway next to a semi. So she shall live to ride another day!!!