Cleaning the oil cooler

[Mike Smith]

Let me save some of my breath on Sunday
How much if this have you tried / thought about ?

Overheating can be caused by a number of factors.

1. A high Ambient Temperature
2. Low Oil Level
3. Incorrect Gauge Readings
4. Incorrect Ignition
5. Incorrect Carburation
6. Dirty Engines
7. A worn and tired engine
8. Engine Design
9. Oil
10. Also see Ron LaDow`s comments at the end of this screed

High Ambient Temperatures - are something that will affect the running temperature of your 356 motor. However, it is not something that we usually suffer from in the UK but it is something to consider if you are in the South of France in summer. Do not panic until you have given it some thought

Low Oil Level - It is important to remember that our engines are as much Oil Cooled as Air Cooled, so low Oil Level means less oil to absorb and disperse the heat

Incorrect Gauge Readings are common – This is the most IMPORTANT Gauge on the dashboard and before playing with anything – CHECK what this gauge is `Actually` reading.
a) Remove the Sender from the Engine - extend the connecting Wire.
b) Wrap a separate bare`d wire around the body of the sender and earth it to the car
c) Place the sender in a kettle of water and boil it – With the ignition turned on, your gauge will now tell you where 100 C is on its scale (212 F) – remember to turn the ignition off or you may damage the coil
d) 100 C is the normal operating temperature although there will be variations depending on the ambient temp and altitude.
e) The needle should be pointing almost vertically upwards, although this is not super critical. What is important is know where 100 C `Actually` is on the gauge. If it is wildly off centre, suspect the Gauge or the sender.
f) Be aware that you the gauges, that are currently being re-built, do not work with the old style senders (this applies to Palo Alto Gauges I have no knowledge of other restorers)
g) Early 356 Gauges were marked with the temp. numbers. Porsche eventually did away with these numbered markings. However, if you look upwards, towards the underside of the bezel, there are still markings (they are VERY hard to see)

Incorrect Ignition Timing – Retarded Ignition will generate more heat that will eventually be passed to the Oil.

Incorrect Carburation – Weak fuel settings will generate more heat (at high Revs) that will eventually be passed to the Oil, it will also damage the Pistons

Dirty Engines – Engines that have not had proper servicing for many years or been abused still by their owners still appear from time to time. The largest problem is an accumulation of Oily debris spread over the cooling surfaces of the Oil Cooler, Cylinders, Cylinder Heads and the inside of the Fan Housing. We also see them where the Oil pump is attempting to suck Oil from a sump full of sludge and cooling surfaces are coated with fibres from a rag that has, at some time in the cars life, disappeared into the fan. `Cleanliness is next to Godliness`

Worn and Tired Engines – Heat from the engine is generated by the explosions that are going on within it and this, of course, is in the cylinder head area. The heat from this area is dissipated by the transfer of heat via a number of areas but those to be considered are
a) The Valves which in turn transfer the heat to The Valve Guides and thence to the Cylinder Heads
b) The Valve Seats transfer the heat in the same way as the guides
c) The Cylinders
d) The Pistons and Rings
The incoming Fuel mixture also cools the hot area and eventually a considerable amount of all the heat being generated also disappears out of the Exhaust Port

Engines eventually wear out and as the clearances between these components increases. The contact area becomes less, so does the ability to transfer the heat. An engine that ticks all the boxes 1 thru. 6 and is starting to run hot, is probably becoming worn in the areas mentioned. The first area where this is usually obvious, are worn Valve Guides or damaged Piston Rings. A Leak-down Test and a Compression Test will tell you whether these are areas that should start to be investigated

Engine Design – Early 356 Motors had Small Oil Pumps – a Small Oil Pump Suction Tube – less efficient Oil Coolers – Early Fan Housings (less efficient) and a different number of blades on the Fans. Porsche rectified all these points in later engines and even a worn Engine can be made to run cooler by the retro-fitting of some of these items.
a) Small Oil Pump Engines – should just be treated with the respect that they deserve. PRS are working on a simple modification to increase the output of these pumps
b) Small Suction Tube – this is not an essential item to consider, unless you are building a race motor
c) Oil Coolers - this is an area where a little extra cooling can be gained by the fitting of the latest Aluminium Oil coolers that are now available
d) Fans – Early Fans had 16-blades – Late fans had 28-blades. It makes sense to fit a Late Fan to all 356 engines, although it will eat a little more power from the motor
e) Fan Housings – Porsche did away with the Wire Screen on the Fan Opening and fitted an Involute Entry. This increased the efficiency of the Housing itself and again it does make sense to fit these to all 356 engines
f) In Addition – Fit a proper Fan Belt (without inner teeth) - the size is 9.5 x 825
g) Fit the Heat deflector between the Flapper boxes - everything helps
h) In Addition - If `Money is Tight` and you really need to drive your 356 a few more times before the major strip down, you could fit a Larger Crank Pulley and spin the fan a little faster. PRS do have these for the later engines - they are not the same as a Pre. `A` pulley. You could also i) PRS are also working on - a modified gearbox which will allow you to cruise at lower RPM`s without the loss of the correct `Spacing Drops` between the gears. This NOT just adding a higher top gear – We have `been there and done that` although I still run my own car with a 4G top gear.

OIL – I am not going to get into any discussions on Oils except to say that we do not like Full Synthetics for 356 Engines. We have used and are happy with Gibbs – Millers - Kendal and Valvolene Racing (Valvolene is the one we use everyday)

Oil Filtration – although this does not link directly to the subject of heat, a properly fitted modern High Efficiency Oil Filter will add oil to the engine and if it is fitted in the air stream will also add cooling to the oil. It should NEVER be fitted in the engine bay – that is just adding heat to area that you want to be ambient – both for cooling purposes and for efficient carburation

If I have a made a Boo Boo anywhere in my thinking, I am happy to be corrected

Mike

@@@@

Additional Comments by Ron LaDow

I think I'd add some comments about the *car* being in a good state of tune.

Heat is the by-product of engine power.
Usually, it takes very little power to move a (correctly set-up) 356 smartly down the road, so you should not see overheating
.
However, mix in some dragging brakes, maybe dry front wheel bearings, some hot-rod gum-ball 8" wide tires (or even just ones down to 15PSI), perhaps a car that hasn't seen an alignment rack for twenty years, or misadjusted emergency brakes, and suddenly, your engine is required to make 25% more power and waste heat at the 75% IC inefficiency rate, and you'll see the problems.

[neilbardsley]

Pretty much done everything that Mike suggested.

Checked infra temp gauge against boiling water

Got an analog rpm counter which tie in nicely with the in car rpm counter. Digital is overrunning.

Seen that the dwell angle isn't stable as rpm increases. Goes from 49 to 43. I think this means the dizzy needs looking at.

Set advance to 35ish

Balanced carb idle

Set mix and checked the change in rpm as I remove spark plug leads

Changed the oil

Now running even better and on a couple of short runs appears to be running cooler.

I'm very hopeful for the run to Hedingham tomorrow.

Finally treated the car to a polish

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[neilbardsley]

I finally braved checking the sender and gauge. First I decided to check the temperature of the water



The digital gauge and thermometer agree.

Next I removed the sender from the engine and it broke!




Probably explains the mis-readings.

I've called PRS about getting a sender and agreed to send them the gauge so they could match.

On the back from I stopped at a petrol station to check the temperature of the fan housing and dipstick by touch. They seemed OK.

I'm not so concerned the car is over heating
I called PRS about

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[neilbardsley]

Panel installed from, Mike Smith, to shield the oil pump from the exhaust



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[neilbardsley]

I removed my distributor to send any to be restored. The first thing I noticed is I have a 022 not BR18!

It not clean inside but the main issue is the dwell angle isn't stable

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[Nine One One]

Neil
If not for originality, there is nothing wrong with a 0 22
Plenty of 356’s and 912’s are running 0 22 I have one built by Glenn Ring

The advance curve is not too far out from an BR18 and it peaks higher as well

http://postimg.org/image/70sder60b/

Ian

[neilbardsley]

That was my understanding too. Since it's a cast iron version that is good

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[neilbardsley]

I drove the car up/down to Chester on the weekend. It ran very nicely. I managed to glue back the temp sender back together after breaking it and it was still giving a reading The reading was still higher even with the oil pump protection panel installed. I pulled over twice one on the way up when the temp gauge said 220F+ and another time on the way when I had been running quite close to 240F for a while. I was able to touch the fan housing and dip stick. I would say they were warm not hot. If I understand correctly this is reasonable test so I decided to drive and ignore the gauge. Well within limits I didn't go above 240F even when running quite quickly on the M6 toll road.

I didn't have the energy left on Sunday evening to test the sender/gauge in boiling water after removing the distributor but will try next weekend.

[neilbardsley]

Two weekends without touching the 356! Although I did spend some of the weekend trying to rust proof our daily car!

I just got an email back from the Lee at H&H who is rebuilding my distributor. My 022 was advancing too quickly. He is going to return it to origiinal spec. He didn't say anything about the dwell angle not being stable but I asked him to confirm that is part of the rebuild. I can't see why it wouldn't but it never hurts to have it in writing.

Data for 0231 129 022
0 @ 400
6 @ 600
8 @ 800
10 @1000
12 @ 1200
14 @ 1500
15 @ 1700

Your Distributor

0 @ 200
2 @ 300
4 @ 450
5 @ 500
9 @ 700
13 @ 900
14 @ 1100
15 @ 1500

[neilbardsley]

I emailed H&H to ask them how they were getting on with the distributor rebuild on Tues and got a reply to say it had arrived back from the platers. Which confused me because I didn't know they were going to replate it? Just cleaning it up and getting it working was enough. They said maybe it will be ready end of last week but that has come and gone.

I finally got around to checking my temp sender and gauge with a cup of boiling water, as per Mike Smith's suggestion. I found that my old sender was over reading by 10F. The mercury thermometer said 180F while Mrs B said it was about 190F on the in car gauge. The replacement sender was under reading by 30F so I decided to put back the old one in. However, it came apart as I put it back in (in almost exactly the point as it had before) so the replacement sender when back in. 30F under certainly means I will have to try and recalibrate as some point.

[vwgillybilly]

Common sense has surely got to prevail at some point.....

Gill

[neilbardsley]

Distributor back but probably not going into the car until after I get back from holiday

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[neilbardsley]

A couple of frustrating hours today. I cant get the engine to fire with the distributor back in. Firstly I didn't push down far enough so the rotor arm wasn't turning. Next I installed to the wrong tdc. Which meant some every loud back fired. Value covers off to find Tdc 1. Distribrutor installed but still not firing. I checked the points gap which was too wide so I adjusted to .4mm. Strange that it did come back correct when I asked them to set to 50 degree dwell angle. I've checked I've got the leads correct 4 times. I going to think on it over night

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[neilbardsley]

What a frustrating few hours wasted. The gear that fits into the driver gear was fitted 180 degrees out! Many thanks to Chris Turner for helping me debug. Was going to send back to H & H but in the end figured out how to remove the pin and rotate the gear by 180 degrees. After reinstalling I got the engine running again.

I was questioning my sanity until it I realised the expert distributor rebuilders weren't quite so expert! Another lesson learnt. As Mick Temple once told me assume nothing and check everything.

[mycar]

I presume that by the time you had the distributor sorted there was no time to turn the engine ?

Very frustrating to entrust your dizzy to a company you thought were more than competent only to be let down by lack of attention to detail like this. I trod the same path and in the end sent my 356 distributors to Ed Fall at Vintagewerks in the States, a lot of faffing about but then you know the job's been done right and you can tick the distributor off.

Keep going, all this slow progress adds up to become invaluable experience. Sometimes it seems the actual driving of the car is merely a by product of working on it.

Looking on the bright side, the roads will be awash with salt before you know it and the cars will be grounded anyway. Plenty of time to get things running well over winter, ready to emerge like a fluffy chicken firing on all four cylinders come springtime.