Still vapor locking....not!

[crvc]

I've posted ad nauseum about my engine overheating woes. I had two restored blocks but both had vapor lock problems. Two years ago I posted about a trip down to Utah in my '67 with a rebuilt DP 1640cc stock engine. I ended up broken down with vapor lock. I spent the next two years trying to fix the problem. A few weeks ago I made the trip to Utah again. After an hour traveling at 70mph I checked engine temp using a laser thermometer. The block was 260 degrees. Laying on the ground and pointing the laser at exposed fins the temp was over 300 degrees. Coming back home I had vapor lock again.

I just put in a new cooler and hoover bit. Today I repeated the trip south. After an hour the block was 200 degrees and the fins were 240 degrees. Back in town the block was up to 210 degrees but the fins were down to 230 degrees.

Ambient temp is nearly 90 degrees today. It never gets hotter than that here. So the vapor lock problem is finally solved. Thanks again for all the help and advice.

kevin

[aussiebug]

Good to know Kevin, although 300+ CHTs are not uncommon in bug engines and that should not be causing vapour lock.

I once thought I had a vapour lock problem that was driving me batty. I eventually tracked it down to the fact that I have a 71 doghouse engine (larger fan) in my 68 with a solid engine lid, so it was overheating every time I drove over 50mph (not enough air inlet area for the larger fan). I put a 1970 "two-slot" engine lid on the car and the problem completely disappeared, even in 110 f ambient temps. Sometimes the fix is simple, when you can find the source of the problem.

[Piledriver]

I suspect he had an internally "expanded" oil cooler with ~zero airflow, although the early decklids with late fan are certainly a known issue, as well as the early narrow fan belt on late alternator/doghouse setups.
(Marc suggests it's the alternator, but the fan draws ~10X the power, so I'll pretend the bigger fan is more the issue)

Might want to link to the related thread where this got extensive discussion in case anyone else runs into something similar...

[Marc]

Wasn't 'til the inception of the alternator that the wider belt was found to be needed - the early dualports with generators all had the wider fan too, even the Bus/Thing with 38A generator got by with a 9.5 belt.

[crvc]

http://i1325.photobucket.com/albums/u63 ... 69e850.jpg

IT's a '67 bug and had the solid engine lid. On the first trip south I had vapor lock after only an hour driving. That led me to 2-years of online suggestions which led me nowhere. Ultimately I was given an engine lid off a later model bug. As the photo shows, I cut out and welded in the vents. On the recent trip south the vapor lock didn't occur til I was nearly home, a three-hour drive. So I'm guessing the 300+ CHT in Utah turned into something much hotter later in the drive. The important point is the CHT stayed in the 200 range for the more recent trip.

An 'internally expanded' oil cooler might have been the problem. I bought the '74 bug for $100 because it had a broken engine. A rod had broken and cracked the case. I assume it had overheated. I moved the shroud, tinware and oil cooler to a new block.

Another problem though....doing 70MPH coming around a curve I encountered a herd of antelope sauntering in the middle of the road. Hitting my '67 brakes did little. Then I hit the horn. The BEEP! BEEP! made the last guy sprint and he missed my bumper by inches. So I either need a better horn or disc brakes?

Thanks,

kevin

[ALYKAT III]

http://i1325.photobucket.com/albums/u63 ... 69e850.jpg

IT's a '67 bug and had the solid engine lid. On the first trip south I had vapor lock after only an hour driving. That led me to 2-years of online suggestions which led me nowhere. Ultimately I was given an engine lid off a later model bug. As the photo shows, I cut out and welded in the vents. On the recent trip south the vapor lock didn't occur til I was nearly home, a three-hour drive. So I'm guessing the 300+ CHT in Utah turned into something much hotter later in the drive. The important point is the CHT stayed in the 200 range for the more recent trip.

An 'internally expanded' oil cooler might have been the problem. I bought the '74 bug for $100 because it had a broken engine. A rod had broken and cracked the case. I assume it had overheated. I moved the shroud, tinware and oil cooler to a new block.

Another problem though....doing 70MPH coming around a curve I encountered a herd of antelope sauntering in the middle of the road. Hitting my '67 brakes did little. Then I hit the horn. The BEEP! BEEP! made the last guy sprint and he missed my bumper by inches. So I either need a better horn or disc brakes?

Thanks,

kevin

Both !!!!

[Marc]

...I bought the '74 bug for $100 because it had a broken engine. A rod had broken and cracked the case. I assume it had overheated. I moved the shroud, tinware and oil cooler to a new block...

I've long had one simple rule when it comes to used oil coolers - never reuse one from an engine that's lost a bearing. Yes, you can soak them in lacquer thinnner, rig up plumbing to flush with solvent for days, blow out with compressed air, etc., etc....but the safest way to avoid being haunted by a plugged one is to not take the chance.
As for one that's "internally expanded" (ballooned so that the air passages between the cores are occluded), they can be detected by visual inspection or by shooting water from a garden hose through between the tubes. In my experience this is seldom an issue with a doghouse cooler - they more typically develop leakage before they'll balloon - but it was pretty common with singleports, especially if they had a big pump (like a Melling) and a "pressure booster" kit. The front (flywheel end) pressure control valve was added to dual-relief cases expressly to prevent the cooler from being exposed to pressure over ~65psi...of course, its function too can be defeated with overkill components and/or too-high oil viscosity, but statistically ballooning is much less likely with the doghouse setup.