|
|
|
|
| Author |
|
|
Registered
Join Date: Apr 2001
Posts: 39
|
determining oil cooler health
My continuig saga of hy cylinder heads being rebuilt is continuing. I just talked to Adran down at HeadFlow master and his diagnosis was that one of my heads was damaged by over heating.
So... I'm thinking of adding an external oil cooler but my more immediate concern is the health of my internal oil cooler. How do I determine its state of health, is there a good relaible way to test for clogs, is there a good way of flushing it. Right now the engine is apart and the oil cooler is seperate so my options for what to do may be expanded. Also, any thoughts on adding an external cooler? sandwich adapter vs. the method in the PP tech article? Locations? I don't think I want to run the lines to the front or cut my front bumper but I'm worried about air flow in the back trunk. How about the deep sump kits, are they worth it? Here's the link to them if you're unfamiliar: http://www.pelicanparts.com/catalog/shopcart/9144/POR_9144_oilsys_pg2.htm#item14 Thanks, - Braxton '74 2.0 |
||
08-20-2001, 12:14 PM
|
|
|
914 Geek
|
Oil coolers don't help the cylinder heads. There isn't an awful lot of oil that winds up in the heads (except when you're cornering). So cooling the oil more effectively won't really do what you want to happen.
The oil traps/oil sumps will not cool the oil that much, either. They increase the radiating surface area some, but not a lot. They add more oil, but that will not cool the existing oil down--that merely means that it will take a bit longer for the oil to get to whatever temperature it is getting to. The oil traps and such are mostly helpful for making sure you still have oil pressure when you go around long sweeping turns with good modern tires and a moderately-aggressive alignment. Your cylinder heads are cooled only by the air flowing over them. That's pretty much it. To make sure that they have enough cooling, you need to do a few things. First, make sure that your stock fan is in good shape. Fans with missing blades are bad, and dirty fans are bad as well. (Thanks to Jake Raby for pointing that fact out!) Make sure your cooling tin is all in place. Make very sure that the flaps underneath the cooling tin are in place. If you removed them, that may very well be why you overheated... Holes in the tin are generally Bad Things; that is why most or all of the holes the factory put in have grommets and seals on them. Install these grommets and seals, or otherwise block the holes. Make sure the threaded plug in the timing hole on top of the fan shroud is in place. This is quite possibly the single biggest place you can lose cooling air. Make sure that your engine cooling fan cannot ingest air from underneath the car. (That means if you have the dealer-installed A/C, try to figure out how to stop air from coming up thorugh that huge hole in the engine tin and engine shelf.) The stock heater dumps warned air out directly under the engine. This does not work as well as cooler air for cooling the engine down. And, when the air is done cooling the engine, it is warmer than before. And it is dumped out underneath the engine. Also make sure that all of the fins on your heads and cylinders are in place and clean and free from blockage. You'd be amazed at the quantity of pine needles and dirt and such that can accumulate on top of the engine. A stock cooling system in good shape should be able to cool a 2.0 quite nicely. Other things to check: Fuel mixture (lean is hot), and timing. (Too far out of spec can make the engine run hotter.) --DD ------------------ Pelican Parts 914 Tech Support A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling |
||
|
08-20-2001, 02:30 PM
|
|
|
Registered
|
Nice job, Professor Darling! Great summary of stock engine cooling issues and fixes.
|
||
|
08-20-2001, 03:51 PM
|
|
|
Registered
Join Date: Apr 2001
Posts: 39
|
So is it worth adding an external oil cooler at all? I'm a stock 2.0 in terms of pistons and cylinders, but the car has been carbed. I'm trying to introduce some sanity to the car after three different POs, non of which seemed to have any coherent idea of what they wanted to do to the car. I'd like to keep things as simple as posible while maximizing the reliablity/longevity of the car.
|
||
|
08-21-2001, 10:33 AM
|
|
|
Registered
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,705
|
Dave is pretty nearly right about the oil and the heads....Big fours generally will run a multi stage external oil pump and roller rockers with drilled adjusters which give much more oil flow to the heads and that grabs a lot of heat before it is sucked back into the crankcase or through additional suctions to the external pump. This is usually only necessary if you go over 2.4L in size or you are really reving the enging hard. This extra oil cools the heads some and also gives lots of oil splashing around the valve areas. The cost of an external pump, dry sump system and cooler is spread out over several engines that each will last longer than without the extra oil system. Good luck.
|
||
|
08-21-2001, 11:37 AM
|
|
|
914 Geek
|
As for needing the external oil coolers, I think you should check things first to see if you need one or not. First step is to make sure your stock cooling system is in as good a shape as you can make it. That's in part to make sure the heads and cylinders get cooled, as well as the oil. Then see if your oil is still making regular trips into the 250F+ zone. If so, an external cooler should be in your future.
And keep in mind that you won't be able to cool nearly as effectively with air that is 100F+ (e.g., Texas summer day) as with air that is 65F (e.g., San Francisco summer day). So if you move from SF to Texas, keep an eye on the gauge. --DD ------------------ Pelican Parts 914 Tech Support A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling |
||
|
08-21-2001, 01:42 PM
|
|
|
|
Registered
Join Date: Apr 2001
Posts: 39
|
Thanks everyone - all the info really helps.
I'm planning on replacing my temp gauge (which was questionable before the head failure). That should allow me to keep track of things better. One question on temp gauges, my cylinder head had a sending unit in it for a temp gauge. Is that normal? That's not the sending unit that's connected normally is it? I've been planning to get both a normal temp gauge and to replace my busted CC clock with a head temp gauge. Will it work that way or have I just been delusional? |
||
|
08-22-2001, 12:30 PM
|
|
|
914 Geek
|
The sender that threads into a hole near the #3 spark plug hole is for the FI. It works on a totally different principle than the commonly-avaliable VDO head temp gauges.
You can hook it up to an oil temp gauge, and it will show you "warmer" or "colder". But you won't know any numbers. (Sounds like the stock oil temp gauge, don't it?  ) But to get meaningful readings, you'll need the aftermarket "ring thermocouple" sender and gauge. Have Adrian cut slots at the 12 o'clock position of the spark plug recess so you can get the sender on the spark plug, the way it was intended to go. Haave him do all four plug holes while he has the heads. That way you can move the sender around if you want to check any one cylinder.--DD ------------------ Pelican Parts 914 Tech Support A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling |
||
|
08-22-2001, 01:37 PM
|
|
|
Registered
Join Date: Apr 2001
Posts: 39
|
How about the VDO Cylinder Head tempature gauge/kit (Part # VDO-310901). Is that what you're refereing to above? Or is it another option?
|
||
|
08-22-2001, 02:16 PM
|
|
|
914 Geek
|
That's the ring thermocouple and matching gauge.
--DD ------------------ Pelican Parts 914 Tech Support A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling |
||
|
08-22-2001, 03:29 PM
|
|
74 Porsche 914 2.0 
1976 Porsche 914 2.0 liter 
