Overheating on the highway. 76, 2.0 Options

[brant]

Also wanted to ask which front spoiler or valance you are using and about ride height

you need some air to flow under the car
temps will go up if the car is too low or if the spoiler is too close to the ground.

brant

[wonkipop]

@SVG223

hey thats a good looking car you got hold of.
i looked at the photo gallery in the link you posted.
seems to be all there, very original and in nice condition.

without wishing to add to lists of what could be wrong -
@emerygt350 suggestion of a blocked cat isn't silly and worth checking.
i can believe that car just might be a 50+K miler and if so might still have a 45 year old cat on the exhaust. i couldn't see if so from the dealer ad photo gallery.

good luck with it and follow the D jet guys advice on this forum.
i own an L jet so wouldn't have a clue when it comes to these.

but don't forget to keep the revs at 2800-3000 out on the highway for aircooled peace of mind.

EDIT - ps checking out that photo gallery your heater hose looks fine and shouldn't be blocking fan air flow. its all beautifully stock in there and in amazing condition. and i got into the full gallery at high res - its still got a cat on the exhaust. (IMG:style_emoticons/default/blink.gif)
it kind of looks original.

[wonkipop]

i got one of those them there grommets on my engine if you want to come to australia to look at it. plenty of beers down here and the govt. has opened the doors to the hermit kingdom (IMG:style_emoticons/default/beer.gif)

sounds like a good tip @JamesM re whats under the tin and on the fins since you guys on the top of the world seem to suffer from mice nest problems? (IMG:style_emoticons/default/sad.gif)

Indeed, we are lacking in enormous mouse eating spiders to help keep the population in check.

May take you up on that beer sometime though, I could use a change of scenery.

we do have mice down here. introduced species (unlike the cute native marsupial mice) and it is a pest when they get into plague proportions out in farm country. happens every 10 years. but they tend to eat everything (like wiring) but for some reason don't do the nest building thing. seem to prefer holes in the ground. maybe something to do with it being hot? not super cold like USA? dunno. but we definitely don't seem to have that unbelievable nest building crazed species that you guys suffer through. i can't believe some of the photos i have seen of what they get up to in your neck of the woods.

its the deadly snakes that get them and keep the numbers down in normal times.
the spiders are more interested in attacking people. (IMG:style_emoticons/default/smile.gif)

[SVG223]

My 914 overheats on the highway. I had concerns about the air flap, but I think the thermostat has broken and it stays in the open position. I thought something might be clogging the fan but it looks clear. I wonder about the heater air hose that goes over the motor. It could be blocking some air possibly. I may try to tie it out of the way. After exiting the highway and stopping at a stopsign the idle was extremely low, I was surprised it was still running. I turned the engine off for a while and it ran better after it cooled down. Any ideas would be appreciated.

Does the engine have a catalytic converter? Clogged converter will create back pressure causing overheating. ‘76 my in California had them.

Yes, it does. I found a receipt where it was replaced in 2005 or so in California.
I wouldn't mind being rid of it. I'm not sure how to check the back pressure.

[SVG223]

As James said that is the oil temp. Porsche actually changed the gauge markings at one point because it alarmed owners. I've got a '76 and it has always read just as yours shows. Well for the past 13 years anyway. Get a head temp gage if your concerned about engine temps. (IMG:style_emoticons/default/beerchug.gif)

Thanks! Good info!

[SVG223]

The other symptoms point to something out of the ordinary. I would check your plugs for lean conditions, check that timing, look for detritus in the cooling fins. What does your oil look like? If it is low it heats up real quick too.

And buy yourself a cht gauge. Dakota digital makes a nice one and you can install it without cutting your heads up.

I will check the plugs. The oil looks clean.
I think the mechanic that just did the valves checked the timing and went over the car and said it was all good. He may not have driven it far enough for it to get hot.

[Chaznaster]

The other symptoms point to something out of the ordinary. I would check your plugs for lean conditions, check that timing, look for detritus in the cooling fins. What does your oil look like? If it is low it heats up real quick too.

And buy yourself a cht gauge. Dakota digital makes a nice one and you can install it without cutting your heads up.

@emerygt350 do you have a part no handy for the Dakota gauge you mentioned? Thx.

[wonkipop]

My 914 overheats on the highway. I had concerns about the air flap, but I think the thermostat has broken and it stays in the open position. I thought something might be clogging the fan but it looks clear. I wonder about the heater air hose that goes over the motor. It could be blocking some air possibly. I may try to tie it out of the way. After exiting the highway and stopping at a stopsign the idle was extremely low, I was surprised it was still running. I turned the engine off for a while and it ran better after it cooled down. Any ideas would be appreciated.

Does the engine have a catalytic converter? Clogged converter will create back pressure causing overheating. ‘76 my in California had them.

Yes, it does. I found a receipt where it was replaced in 2005 or so in California.
I wouldn't mind being rid of it. I'm not sure how to check the back pressure.

probably not easy to check exhaust back pressure on 914 of that vintage.
modern cars you plug into 02 sensor in front of cat.
someone on this site might know how to do it if sensor plug in not available.
your mechanic may even know how to.

a couple of weeks ago one of our circle brought his wife's audi into the workshop.
it wouldn't make power properly past idle and it was running slightly hot.
turned out the cat had spat a piece from inside which is like a ring or pipe connector and this had turned sideways in the outlet pipe and was blocking it.
cat was not that old either, but it was an aftermarket cat.

you might be able to get the cat off to inspect it visually.
likely to be a pain in the a with stubborn nuts.
your mechanic could do it.

[emerygt350]

1- ODYR/SLX-11-1--BLUE-K - Cylinder Head Temperature
Color: Blue
Bezel/Trim/Finish: Black
@ $124.95 ($124.95)
1- SEN-11-8 - Cylinder Head Temperature Sender Length 18' for 14mm spark plugs @ $26.95 ($26.95)

you don't need 18' feet.

https://www.dakotadigital.com/

[JamesM]

There's a little wear on second gear synchro and a few other things that make me think it couldn't be that low of mileage.
Here is a link to the dealership that I bought the car from they have a bunch of pictures of it. https://www.driversource.com/vehicles/1385/1976-porsche-914

Whatever the mileage, that thing looks to have been very well taken care of.


As mentioned a plugged CAT can cause issues for sure, but that would probably cause you issues everywhere, not just oil temps on the freeway. Still probably worth pulling it given you have disabled the smog pump as well. My bet is still on gunk in the oil cooler/engine fins being the primary issue. Your cooling tin/screws/fan housing looks way to pristine and original, I dont think they have ever been removed so most likely have 50 years of crud in there.


When you do sort it out though (or maybe even before) get rid of those KYB shocks and replace them with literally anything else. It will feel like a whole new (and much nicer) car.

[mgphoto]

Remove the cat, there is an after market bypass pipe that can replace it.

[SVG223]

Based on info above I'm more convinced that something isn't right. You should be able to run those speeds, at those ambient conditions all day long without issue.

First thing I would do is verify the part number on the oil temp sender. It's free and easy to do. This at least gets us to a baseline where we know about what temp you're oil really is.

I'm not suggesting that is the problem but it is one of symptoms that got your attention.

Next, I'd get a cheap boreoscope, Amazon, iphone app, whatever. They are pretty cheap.

Make sure you don't have the oil cooler plugged with debris or one of these situations (all 3 came from my own tear down core engines -- 3 of 3 had what would be fatal blockages if you tried to run like this):






Blocked oil coolers are amazingly common on these older cars and there isn't an easy way to clean them as annual maintenance. The rodent problems are very real for vehicles stored a good part of the year. Likewise, mice can build one of these nests very quickly - just a matter of a few days.

Next up: Verify timing and make sure you're not running with too much advance.

We haven't talked about what you're running carbs or fuel injection. Either way, you need to verify that the fuel system isn't running lean. This can be as basic as reading the spark plugs.

As previously mentioned by others a cylinder head temp gauge on Cylinder #3 is a real good thing to have since head temperatures lead oil temperatures by a wide time margin. By the time you see the oil temp going up, the heads have been hot for a long while.

Thanks for these pictures they give me an idea of what could be happening. Stock D Jetronic. A head temp gauge would be nice, ideally, it would be a vdo gauge in place of the clock in the center console.

[FlacaProductions]

1- ODYR/SLX-11-1--BLUE-K - Cylinder Head Temperature
Color: Blue
Bezel/Trim/Finish: Black
@ $124.95 ($124.95)
1- SEN-11-8 - Cylinder Head Temperature Sender Length 18' for 14mm spark plugs @ $26.95 ($26.95)

you don't need 18' feet.

https://www.dakotadigital.com/

true - you don't need 18' but remember that you can't just cut/shorten that lead.

[Lockwodo]

Don't know if anyone else has mentioned this, but make sure the fan belt is tight. If it's slipping, you won't get the air flow over the heads that you need to cool them down.

[emerygt350]

That's a Porsche/diff type thing. Our fans are direct mount. Belt only runs the alternator.

[piscean914]

i would start by confirming the oil temp in the sump with a mainly by design style oil temp dip sticks for 914-4's - mainly by design was purchased by ron at precision matters - i only see 356 oil temp dip sticks on his site - there are also gene berg type iv oil dip stick sensors as well - i would start systematically with the accuracy of the oil temp gauge before chasing other issues - i have a thermostatically controlled external oil cooler, custom mount, w/fan, after years of experimenting with verified oil temps - hope this helps

http://www.914world.com/bbs2/index.php?showtopic=334157

[Chaznaster]

1- ODYR/SLX-11-1--BLUE-K - Cylinder Head Temperature
Color: Blue
Bezel/Trim/Finish: Black
@ $124.95 ($124.95)
1- SEN-11-8 - Cylinder Head Temperature Sender Length 18' for 14mm spark plugs @ $26.95 ($26.95)

you don't need 18' feet.

https://www.dakotadigital.com/

Thank you.

[rhodyguy]

Delete/Replace the cat converter and clean the oil cooler. The cooler will be a bit of a chore. Purchase new cooler seals (I would get 2 sets. They keep.) before you start the process.

[SVG223]

I think the ignition timing has been retarded by a bunch. I just turned the distributor counter-clockwise enough to increase the idle by 1000rpm and it ran better, so far no overheating but it's not summer yet. I need to get a timing light. I tried to get it to ping but it didn't so I need the light. It is running well so far.

[Superhawk996]

tried to get it to ping but it didn't so I need the light.

You are playing with fire.

Detonation kills engines so fast you would hardly believe it. The ability to hear detonation on an an air cooled engine is impaired by the valve clatter and fan noise.

Get a timing light on it. Stop guessing