914-6 runs HOT - Part 2 Options

[767driver]

Some of you may remember my initial thread about 914-6 oil temps here...

http://www.914world.com/bbs2/index.php?sho...%20hot&st=0

I was hopeful that re-installing the ducts from the fan housing to the heat exchangers would solve my high oil temps. Well...it solved one of the causes of my high oil temps. Now that I have driven the car on 2 multi-day tours through California I can unfortunately report that the issue is not fully corrected.

With the benefit of hindsight I now know that as road speeds increase the airflow through the engine compartment is insufficient to keep the oil temp in check. Running through the gears on tighter 2 and 3rd gear roads are no problem. It's the more open 4th and 5th gear runs (high road speeds) that are causing the problem now.

Now it looks like we are dealing with 2 options. The first is to install a faster-turning 1.9 to 1 ratio fan setup. This will increase airflow through the engine compartment but will make more noise and take a few HP to run. The second option is to add an external oil cooler. The front-mounted cooler seems to be the tried-and-true solution but is expensive and invasive. Some folks have rigged up an external cooler with fan under the rear of the car.

I am soliciting thoughts, preferably from those with experience themselves, on these or any other options that may exist. I would appreciate any pictures of the various external oil cooler installations as well.

Many thanks,
Lee

[frankiec@outrageous.net]

I have a 3.2 with the oil cooler mounted in the passenger side rear wheel well. No problems with high temps at any speed.

Good luck, Tom

[mepstein]

I would think a rear mount cooler might do the job for you. If you want to really max out your cooling capacity, do the front location.

[brant]

I run the faster fan speed system and found minimal heat relief. Mine is a race car so the rpm of the fan was pretty high before and after playing with the pulleys

The oil cooler is the guaranteed route to lowering your temps.

[767driver]

I have a 3.2 with the oil cooler mounted in the passenger side rear wheel well. No problems with high temps at any speed.

Good luck, Tom

Is this something "home-brewed" or did you buy a kit somewhere? I would love to see pictures showing the cooler installation and the routing of the lines.

[porschetub]

Some of you may remember my initial thread about 914-6 oil temps here...

http://www.914world.com/bbs2/index.php?sho...%20hot&st=0

I was hopeful that re-installing the ducts from the fan housing to the heat exchangers would solve my high oil temps. Well...it solved one of the causes of my high oil temps. Now that I have driven the car on 2 multi-day tours through California I can unfortunately report that the issue is not fully corrected.

With the benefit of hindsight I now know that as road speeds increase the airflow through the engine compartment is insufficient to keep the oil temp in check. Running through the gears on tighter 2 and 3rd gear roads are no problem. It's the more open 4th and 5th gear runs (high road speeds) that are causing the problem now.

Now it looks like we are dealing with 2 options. The first is to install a faster-turning 1.9 to 1 ratio fan setup. This will increase airflow through the engine compartment but will make more noise and take a few HP to run. The second option is to add an external oil cooler. The front-mounted cooler seems to be the tried-and-true solution but is expensive and invasive. Some folks have rigged up an external cooler with fan under the rear of the car.

I am soliciting thoughts, preferably from those with experience themselves, on these or any other options that may exist. I would appreciate any pictures of the various external oil cooler installations as well.

Many thanks,
Lee

I believe you had a heatexchanger issue @ the start,seems weird you have the issue back (IMG:style_emoticons/default/headbang.gif) .
Its hard to say but could this be a new issue ?.
Can't remember if anyone asked if your oil thermostat was working correctly ?,they aren't known to fail often but that wouldn't be helping your cause one bit.
Was your oil cooler cleaned when the engine was rebuilt ?,I don't mean a quick wash out,I washed mine out after a long period of soaking in solvent...it was filthy,I then had it ultrasonically cleaned,the mate doing it said it was still very dirty before that process.
You could change your fan speed but kinda thinking that's only a bandage for your issue really,unless you have the wrong pulley/s to start with.

[patssle]

I tried going without an oil cooler on my 3.0 - no luck. I installed one underneath the rear trunk and the engine is kept cool just fine. Don't need a front cooler IMHO if you don't want one or won't be tracking.

http://imgur.com/a/6u4ew

[767driver]

porschetub...

I do not believe this is a new problem. After the initial heat exchanger fix the problem now manifests itself at higher road speeds...independent of rpm. I believe that it is an airflow issue through the engine compartment at higher speeds. I verified thermostat operation using the T-stat in pot of hot water on stove method...works fine. Oil cooler was brand new when engine rebuilt before I bought car...still had the Stoddard sticker on it.

[IronHillRestorations]

I put a Mocal 24 or 21 row cooler in the right rear fender well and it makes for a neat and easy install without a ton of plumbing, and no loss of front trunk space.

[porschetub]

porschetub...

I do not believe this is a new problem. After the initial heat exchanger fix the problem now manifests itself at higher road speeds...independent of rpm. I believe that it is an airflow issue through the engine compartment at higher speeds. I verified thermostat operation using the T-stat in pot of hot water on stove method...works fine. Oil cooler was brand new when engine rebuilt before I bought car...still had the Stoddard sticker on it.

Sure you have the bases covered just throwing idea's out there,I don't think we get as hot here as you do on the westcoast of the US,we get to 30+ celcuis in the summer my area is one of the hottest of the region in the summer,last summer my 2.2 never ran hot included some rather illegal speeds on my favorite twisty/ hilly back of "nowhere" road.
IMO the rear mount cooler correctly mounted will be some solution,certainly easier than a front mount which you shouldn't need anyway.
I will pass idea's to others now,any of the guru's on pelican come up with anything/presume you have posted on there...good luck.

[buck toenges]

I put a Mocal 24 or 21 row cooler in the right rear fender well and it makes for a neat and easy install without a ton of plumbing, and no loss of front trunk space.

In the front of the passenger side rear wheel? Can you give more details on the plumbing and install?

Thanks,
Buck

[ConeDodger]

First of all, gauge and sender compatible?

Your 4th and 5th gear problem is fan speed. I have confirmed that with CHT. As soon as you go into 5th gear your CHT starts to rise. The rise in oil temp is just the response.

I have a front cooler and an incompatible sender. I've confirmed my temps with a pyrometer as much less than the gauge says...

Bitch is lying to me! (IMG:style_emoticons/default/av-943.gif)

[porschetub]

First of all, gauge and sender compatible?

Your 4th and 5th gear problem is fan speed. I have confirmed that with CHT. As soon as you go into 5th gear your CHT starts to rise. The rise in oil temp is just the response.

Yes very true and there is a drop in oil pressure around 200 + oil temp will be noticeable as the oil thins out,ask me how I know when my gearshift screwed up and I limped home in a high gear...fan speed caused this as well as a hot day.
People get confused about how an aircooled engines works ,its about the oil cooling that has a big impact on running temp.

[BK911]

I still think you have an obstruction partially blocking some engine cooling airflow.

[6freak]

check the cooling hoses ,might have came loose and did you cut the tins between the cylinder's like Bruce Anderson says to do for better cooling ..and what rear valance if any do you have on the car...my temp went up 5 degrees when I put the valance back on.. (IMG:style_emoticons/default/smile.gif)

[767driver]

First of all, gauge and sender compatible?

Your 4th and 5th gear problem is fan speed. I have confirmed that with CHT. As soon as you go into 5th gear your CHT starts to rise. The rise in oil temp is just the response.

I have a front cooler and an incompatible sender. I've confirmed my temps with a pyrometer as much less than the gauge says...

Bitch is lying to me! (IMG:style_emoticons/default/av-943.gif)

I can drive in 4th gear at 4000rpm which is 70mph in my car. Still gets hot. What's the difference between driving at 4000rpm in 3rd and 4000rpm in 4th? The higher road speed and less air coming through engine compartment due to the 914's aerodynamics.

[mepstein]

My belief is that 911 engines get most of their air cooling from the fan. They are often called air/oil cooled engines since oil cooling plays such a critical role. Adding an oil cooler, in addition to the engine oil cooler is pretty well known and well documented. In the 911, early S engines and all later engines benefited from a front cooler Later, when Porsche went to the 3.6 engine, they moved all the oil cooling to the front of the car. It makes sense.

It's actually very easy to add a front oil cooler without "cutting up the car".
1" holes drilled in the sill supports that run behind the rocker panel. Then 2 more 1" holes into the front trunk. About a half dozen 1" holes. Yes, that's all the "cutting" required. You will then remove the rubber plugs in the front trunk and the metal plugs that are seam sealed to the bottom of the trunk floor. Now you have airflow for the cooler. You might then want to create a cardboard template to box in the cooler and transfer the template to some sheet steel that hvac guys use for ductwork. But try running it open at first to see what kind of difference it makes.

Ok, I lied, there is some cutting required - you need to cut an opening in your front valance to allow air to enter the open holes in the front trunk. Radius the edges so it looks nice, similar to a GT valance.

[mskala]

You can get increased fan speed without going all the way to 1:9 to 1.
I may not be recalling exactly but some years ago I used the 80-89 fan and pulley
and with the original 914-6 crank pulley the math makes it about 1.6 to 1 vs. stock of 1.3 to 1.

[Justinp71]

First of all, gauge and sender compatible?

Your 4th and 5th gear problem is fan speed. I have confirmed that with CHT. As soon as you go into 5th gear your CHT starts to rise. The rise in oil temp is just the response.

I have a front cooler and an incompatible sender. I've confirmed my temps with a pyrometer as much less than the gauge says...

Bitch is lying to me! (IMG:style_emoticons/default/av-943.gif)

I can drive in 4th gear at 4000rpm which is 70mph in my car. Still gets hot. What's the difference between driving at 4000rpm in 3rd and 4000rpm in 4th? The higher road speed and less air coming through engine compartment due to the 914's aerodynamics.

What do you consider Hot? My car runs around 200f if its over 80f outside, used to run ~180f when I had a more stock 3.0. I have a front oil cooler.

[767driver]

First of all, gauge and sender compatible?

Your 4th and 5th gear problem is fan speed. I have confirmed that with CHT. As soon as you go into 5th gear your CHT starts to rise. The rise in oil temp is just the response.

I have a front cooler and an incompatible sender. I've confirmed my temps with a pyrometer as much less than the gauge says...

Bitch is lying to me! (IMG:style_emoticons/default/av-943.gif)

I can drive in 4th gear at 4000rpm which is 70mph in my car. Still gets hot. What's the difference between driving at 4000rpm in 3rd and 4000rpm in 4th? The higher road speed and less air coming through engine compartment due to the 914's aerodynamics.

What do you consider Hot? My car runs around 200f if its over 80f outside, used to run ~180f when I had a more stock 3.0. I have a front oil cooler.

Hot?? Hot is top of the white band and into the red hashed band on a 914-6 gauge.