Oil Cooler air flow

[Norm Miller]

The towel wasn't a detour but a roadblock.
Now that you have the back story, you're back to step 1.

[Mark Roth]

I’m sorry I even put anything about the P&C on this. Irrelevant to my question about the oil cooler.

[Jacques Lefriant]

Hi All
There is no right answer to the shroud mounted cooler. With the exception of the 1958 or so engines the oil flow thru the cooler is not thermostatically controlled. the early VW 36/40hp coolers similar to what Zim's sells were not that restrictive to air flow but were not too efficient. Eventually in the VW air-cooled world the fans got more blades and wider the coolers better and the doghouse shroud was engineered. Only in extreme cases the airflow thru the cooler is a problem however engine builders have their preference of the aluminum coolers available which are preferred for their great efficiency and the bonus of less stress on the case. The 5 row cooler is being overhyped with bad data I believe the aluminum 4 row cooler is a better choice for most applications since the air flow should be better than the 6/5 coolers and it transfers heat well.
j

[C J Murray]

The cooler is fine. Get new studs. Use the usual 356 seals. Flatten the surface that the nuts bear on. Do not over tighten. Done.

[Mark Roth]

Thanks C J. That's what we did. The CA builder brought the question up when we asked about his installation modification.

[David Jones]

I think the paper towel could easily be the root cause of the overheating, if it was wrapped around the fan blades circumferentially it may not throw it out of balance enough to be very noticeable, it don't take long if the engine is under load with no air flow. Many years ago in about 1967 I put extra soundproofing on the firewall of my VW bug which worked very well until it detached and sucked up to the fan. No oil temp gauge but I did have an oil pressure gauge and it was the pressure dropping plus a drastic drop in warm air to my feet and a slightly quieter engine that alerted me to a problem. The oil pressure started to drop when driving on a familiar piece of road that would put no unusual strain on the engine. It did not take long to remove the 1/2" thick piece of felt and it never went back in.

[Neil Bardsley]

But the temp never when over 5/8 and Mark said "I heard the whoosh sound right before I brought the car into the shop."

I think Mark is implying the paper only entered the fan for a 1 min and probably not the cause?

[Mark Roth]

Maybe not a minute but maybe 15 minutes. I only noticed it when I was in Hans' neighborhood after I got off the freeway and was driving off from stop signs. The sound was obvious at higher rpms and lower road speeds and I knew something was unusual when I showed the car to Hans. I know that I would have heard that whoosh if it been there before. I know every engine sound, creak and rattle after 24 years. From the photos it looks like the towel was not going anywhere so I think that I heard it as soon as I picked it up from somewhere. Hans first thought maybe it was the towel but then I told him what I said now. Who knows? Maybe it was there longer. The CA builder brought up the older style aluminum cooler question. I wanted to put the cooler question to rest as the towel has been removed. I think that I should have just asked about the cooler without the detour. It seems that the consensus is to keep my cooler. Thank you all for your ideas.
Hill Country Rallye next weekend! A super driving event.
Check out the cool video and the photos. The car is in the 2018 photos.
http://www.hillcountryrallye.org/photos.html

[Martin Benade]

So is the engine back together? With different pistons? As for detours, assuming you know a cylinder got too hot, it is reasonable to consider all possible causes, not just the one you are dwelling on. A number of times I have gotten some explanation for something so stuck in my head that I became certain it was correct, only later to find it wasn't.

[Harlan Halsey]

Years ago, a friend melted a racing speedster engine in two laps at Laguna. The heads warped. The cause was a shop rag which had been left in the engine compartment and was sucked into the fan.

[Mark Roth]

Could be

[Wes Bender]

But the temp never when over 5/8 and Mark said "I heard the whoosh sound right before I brought the car into the shop."

I think Mark is implying the paper only entered the fan for a 1 min and probably not the cause?

Bear in mind that, if you block or restrict the air flow, the cylinders and heads will heat up a whole lot faster than the oil.

[Dick Weiss]

Mark,

Another mentioning; The steel oil coolers just have 6-rows of tubes; Same on the Aluminum coolers unless only 5- or 4- rows of tubes and flat sides.

Dick

[Max Handley]

+ 10 for the paper being sucked into the fan as the whole problem.