914-6 runs HOT - solved? Options

[767driver]

Hi guys,

Lurked here for a number of years and have finally landed a 914-6. It's a 1970 with it's numbers-matching case running a (stock?) 66mm crank and 86mm pistons for a displacement of 2.3L. It runs Solex cams and 40 Webers. It's only got about 600 miles since rebuild. So the engine is somewhat upgraded but nothing too wild.

When I drove it the 45 mostly-highway miles to my house I noticed it was getting a bit warm. The weather was about 60 degrees. The indicator on the factory oil temp gauge was reading about 3/4. The next day I took the car for a nice "getting acquainted" kind of run on mixed highway and country roads. After 25 minutes on the highway at 80 mph and about 3500 rpms it was getting really warm...almost touching the hashed red part of the hot end of the scale. I immediately went over to a buddy's shop and shot an IR thermometer at the rear of the oil cooler. Got temps of 220 or so at top of cooler and 250-260 at bottom. The cooler still has a Stoddard Porsche decal on it. I checked and the cooler is the $1335 German-made part. Oil quantity ok.

Now I know this is not enough motor to overload the factory oil cooling assuming everything is working correctly. I took the thermostat out of the car and performed the pot-of-hot-water-with-thermometer-trick and verified it opens and closes as it should. I guess the in-dash gauge could be wrong, but the IR thermometer seemed to confirm the high reading. All the tins appear to be in place. I have read the cylinder baffles can be installed upside down causing issues. And that the cylinders themselves can be installed upside down. I guess that new-ish oil cooler might be defective...that's an engine drop...right? Ignition timing, cam timing, fuel mixture need to be checked. And none of the cabin heating air tubes are on the car. The 2 supply ducts off either side of the engine cooling fan duct are capped. Is the fact that no fan air is going through the heat exchangers causing the one under the oil cooler to run hot enough to cause the high oil temps? ANSWER: YES

So...what have I forgotten or overlooked here. I had 2 VERY knowledgeable Porschephiles tell me that barring an oil cooler issue it is almost surely a hot bearing (youch!) making that kind of heat.

Any thoughts or ideas are appreciated.

1970 914-6
VIN 9140432125
Engine 6405400

[PlantMan]

(IMG:style_emoticons/default/welcome.png)
Better post some pics cause most of us want to see the car first!!!!!!

[PlantMan]

BTW congrats on the car!

[IronHillRestorations]

260* is too hot, but you can get a spike in temp after you shut the engine off.

It's possible with the performance upgrades you'll have to add additional oil cooling. From my limited experience mag case engines require additional oil cooling in a 914 once you get over 150 hp or so.

If I suspected a failing bearing, I'd drain & strain the oil and cut open the oil filter.

[PlaysWithCars]

Check your ignition timing. Should be ~32-34 at 6,000rpm with the vacuum disconnected and 4 ATC - 6 BTC at idle depending on whether or not the vacuum retard is still intact and working.

If its too retarded it will cause the engine to run hot.

[jfort]

Mine ran too hot and it was tuned correctly. I put in a front oil cooler. Problem solved.

[mskala]

I have almost this exact setup. My cams are Dougherty Cams DC-30 which is a
modernized Solex-type cam.

If you are using the 914-6 (911T) distributor it's not going to be correct. I'm using
a 911E/S distributor with 30-32 degrees advance. There is no vacuum advance
obviously.

What settings do you have on the carbs? You could be running lean.

Maybe your fan air deflector behind the alternator is pointing the wrong way?

Yes, cam timing can cause extra heat.

It is possible to remove the oil cooler without removing the engine but it's not
worth the extra effort.

Do you know exactly what the heads are? Not that they would cause the problem
but the settings on ignition and carbs I use wouldn't be good for you if the heads
are not 2.2L basic heads.

[mb911]

(IMG:style_emoticons/default/agree.gif)

I have a similar engine I am building though mine started as a 2.4t and now is a 2.4 with ported heads 2.2 s pistons and soles cams. I will use a front oil cooler.

[BK911]

If the car sat it could have mice nests on top of cylinders.

[gereed75]

Timing will have a dramatic effect on cylinder head temps. Advanced timing will cause higher CHT's, especially with higher compression ratios

Richer mixtures can also help reduce CHT's. the correlation is obviously lean mixtures raise CHT.

Higher CHT's equate to higher oil temps.

I run a 2.4 with the D.C. 30 cams and 9.5 CR 32 degrees advance on a T distributor. I ran a wide band O2 sensor to tune the webbers and it runs a bit on the rich side (pretty much in the 11-12 AFR under any load). With the stock 6 oil cooler the Temps runs around 180 -220 with normal street driving. Hard driving does elevate temps quickly on hot days.

No reason you should not expect about the same. Check the timing before getting more serious.

I am installing a rear mounted cooler with fan and ducting to pull "cool" air from the wheel well so hopefully I can run it without restriction.

[rgalla9146]

Have you checked the fan belt ?

[Rand]

Have you checked the fan belt ?

I thought he was talking cooling, not alternator? (Ah yes, 25 or 6 to 4... Never mind, I was thinking direct impeller like the 4s.)

[mskala]

Also I did some experiments and running without a deck lid lowers the temp
at least on the highway. So getting one of those GT lids with all mesh should help.

[sixaddict]

something up...should not need added cooling at current temps

[porschetub]

All the right answers from many,but the OP has failed in posting anyway the key points he hasn't completed are the main reasons for overheating,1970 engine is most likely running Weber's as per stock jetting ...don't know cause he didn't say,they are set lean from day one,the increase in displacement will only make that worse (lean condition) ,timing is very important also 34 degrees @ 6000 and no more.
I would say he will maybe have higher compression and that adds to the problem as mentioned.
I have a slightly modified 2.2T stock Marelli dizzy set slightly retarded and run 185 to 190 in hot weather,had a shifter linkage issue and limped home in third gear got to 200+ due to slow fan speed.
Oil pressure is a great test of running temp in these motors,they get hot it drops fairly fast.
See no point in pulling the oil cooler that won't fix anything,not that hard to do ..ask me how I know,no need for a front cooler in a motor that size.
Think the OP should provide all info then some full answers will be forth coming.

[IronHillRestorations]

To summarize in order of ease:

Check fan belt.

Confirm gauge accuracy.

Drive it hard with the engine lid off.

Make sure the timing is dead on the nuts, in particular not excessive advance.

Check the air fuel ratio to make sure you are not too lean, too lean=higher temps.

Check for mechanical obstruction of air flow (mouse nest on cylinders/ oil smeg).

[rgalla9146]

Advanced timing will lead to hard cranking and pinging.
Retarded timing will lead to elevated temperature.

By the way....your car is beautiful !

[forrestkhaag]

Beautiful acquisition. My favorite color (IMG:style_emoticons/default/smilie_pokal.gif)

You may want to consider the simple installation of a Carbon Fiber-fiberglass engine access hatch. This kit makes addressing several of these issues very easy to check. as well a routine 6 maintenance.

i.e., belt tension and changing, timing mark visuals, dizzy adjustment for advance/retard issues, inspection of alternator cooling fin direction, etc.

The photos are using my type four engine to show how much of the firewall is opened up for a 6 installation / my 6 goes in next month so I will update photos.

Good luck with the overheat issue.

(IMG:style_emoticons/default/beerchug.gif)

[toolguy]

Timing. . mixture/carbs. . or this. . . all the missing pieces from the previous owners car cover were finally located. .

[767driver]

Thanks for all the replies...and keep them coming!

Some of my thoughts and responses...

I hear the calls for a front-mounted oil cooler. I really don't think, based on all I have read/heard/seen over the years, that this particular engine should need another cooler. I could be wrong...but it's just not that much more motor than the stock 2.0

Ignition/distributor and carbs are all on my short list. This car was "dyno-tuned" at a reputable shop before I bought it...probably within the last 12 months. ALL of that should have been set up correctly. Will verify...

I have seen ZERO evidence of rodents. Having said that, the air flow through the fan housing and engine tins/baffles will need to be checked free and clear.

The belt seems properly tightened by deflecting it with my finger. It sounds like it is turning at the proper speeds when driving (based on my "ear" for my 911's engine sounds).

This car already has the replica 916 double-grilled engine lid on it.

Oil pressure was mentioned by user id porschetub. There is an auxiliary gauge pod installed containing an oil pressure gauge. The engine has 60PSI or a bit more when cold at fast idle. It slowly looses pressure as the temp rises. It was showing 30PSI at about 3000rpm when the oil was real hot.

Gauge accuracy... is there a better way to verify that than pointing an IR thermometer directly onto the oil cooler itself?

And finally the firewall engine access hatch mod was discussed. I am not sure I want to cut an original 914-6 for the added convenience...which is significant...of that hatch.

I think my first action will be to perform an oil change and look for rebuild-related swarf in the sump screen and oil filter.