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Posted by: Daiberl Aug 12 2012, 09:43 PM

Hello,

I need some help, I finally fixed all my vacuum leaks, the car idles fine, have a Hot Spark installed, and timing seems to be OK. Today I drove the car a bit and after a while the temp gauge indicated that the car is running hot, the needle moved over the P of TEMP before I decided to stop and take a break. After 30 minutes I started the car again and drive immediately home, needle again indicated that the car is running to hot.

Before I fixed all vaccum leaks the car was running like ... but the temp stayed consistent in the middle, so I assume the gauge is fine.

What to check, the knob on the ECU is already all the way to rich.

- Juergen

Posted by: kerensky Aug 12 2012, 09:56 PM

Check for simple things first, like a plastic Wal-Mart bag sucked into the fan. Slipping or broken fan belt. Is all of the cooling tin in place?

Posted by: Daiberl Aug 12 2012, 10:00 PM

All cooling tin in place, fan is working and free of all backs and so on

Posted by: messix Aug 12 2012, 10:02 PM

it's been sitting for a while.... any mouse houses in the tin?

Posted by: kerensky Aug 12 2012, 10:03 PM

Have you driven extensively since installing the hot spark device? Could a connection at the temp sensor have come loose or just not be completely making good contact?

Posted by: Daiberl Aug 12 2012, 10:12 PM

No mice in the tin, we have cats around the house (not ours) and the garage is always closed, I believe it's something technical and it started after installing the Hot Spark. I don't want to switch back to points, the car idles really fine when warm now, not as previous with 1600 RPM. Also have a new engine wiring harness from Jeff Bowlsby installed, all new vacuum hoses. What else can make the car run hot and nearly into the red?

Posted by: messix Aug 12 2012, 10:15 PM

we're talking oil temp right?

Posted by: Daiberl Aug 12 2012, 10:28 PM

Yes, oil temp, the standard gauge in the center console.

Posted by: messix Aug 12 2012, 10:59 PM

recheck timimg, oil level, running 10-40 oil? the cooling flaps in the full open position?

Posted by: Daiberl Aug 12 2012, 11:21 PM

I will re-check the cooling flaps, oil is 10-40, oil level at the top of the scale. Timing checked now 3 times, maybe I need some help checking it again just to make sure it's really OK.

Posted by: euro911 Aug 13 2012, 01:57 AM

I'd double-check all the vacuum hoses for proper routing and connections first.
Are there two ports on the vacuum canister on your distributor?
Are the advance and retard hoses plugged into the correct ports?

I'd also try reinstalling a set of regular contact points in the distributor just to eliminate the 'Hot Spark' module as a possible cause, although changing to a solid-state point system shouldn't create overheating issues.
Does the engine pre-detonate (ping) on hard acceleration?
If so, try retarding the timing a few degrees.

Another item you might check out is the pot (potentiometer) for the richness control. It could have gotten some debris in it and not providing the ECU the proper voltage level (think dirty volume control on an old 1970's era radio)
Try turning it back and forth several times to see if it cleans up the wiper.

Posted by: The Cabinetmaker Aug 13 2012, 04:08 AM

First, you don't state the year and engine size. Second, the timing"seems" ok? Did you actually time it with a light? "seems ok" isn't good enough. Changing to a "hot spark"won't make the engine run hotter. Running it advanced will.

Posted by: hot_shoe914 Aug 13 2012, 05:10 AM

I had this problem was. Turned out to be a simple fix. I unplugged the temp guage and it has never run hot since.

Posted by: rnellums Aug 13 2012, 07:02 AM

I had my temp gauge do this once and it ended up being a bad ground at the gauge.

Posted by: 76-914 Aug 13 2012, 07:38 AM

Assume nothing! Check the oil temp with a known working instrument e.g. an IR thermometer aimed at the pan where the sending unit goes, your wife's cooking thermometer, anything. Just don't assume. with Curt on the timing. Also, recheck your valves. Better too loose than tight.

Posted by: Daiberl Aug 13 2012, 08:24 AM

I will have time again on Wednesday to work on the car (btw, it's a 1974 LE with matching engine), I have to fly to Chicago utnil tomorrow evening so no Teener wrenching. Advance port on distributor is connected, retard not just as it was from factory. Distributor is rebuild with brand new points, ... Plan is now:

• re-check timing
• re-check vacuum hoses
• check cooling flaps
• do valve adjustment

If that doesn't help I will install points again and will check

Posted by: poorsche914 Aug 13 2012, 10:17 AM

If you haven't already, be sure to have Jeff Bowlsby add it to the http://bowlsby.net/914/CanAm/

Posted by: Daiberl Aug 13 2012, 10:50 AM

It's in the registry since I found it 3 years ago after being in storage for 20+ years.

Posted by: JRust Aug 13 2012, 11:39 AM

I know you said the ECU is turned to rich? How do you plugs look? It may just be running to lean. Doesn't the MPS control the fuel ratio more than the ECU? I obviously don't know jack $hit. My LE is running hot too & I know it is because it is running lean. Mine really only get's hot on the freeway in warm weather though. I've heard of using a potentiometer to make sure it is getting the right signal for fuel. I don't know how to do that though . I'll be watching your thread to see what you figure . Although I am getting damn good MPG at 32!

Posted by: Drums66 Aug 13 2012, 11:48 AM

....Those (temp guage)are not very accurate to begin with! did you even
mess with the timing??

Posted by: Dave_Darling Aug 13 2012, 03:18 PM

That is backwards. The retard port (the one pointing toward the distributor body) should be hooked up to the fitting on the throttle body that points away from the distributor. The advance port (points away from the distributor body) was left unconnected and unplugged from the factory.

Mixing those up could possibly have an effect on your oil temps.

I am more inclined to believe there is still something obstructing the air flow to or through the cooler. Or that the gauge is not reading correctly. Verify the actual temperature when the gauge reads hot. If it's under 230F, you should be OK. If it's 250F or over, it is very definitely a problem.

--DD

Posted by: minnesota loon Aug 14 2012, 06:23 AM

What happens to engine when temp is 250? If oil pressure is good why does 250 matter? Race cars run hotter. Porsche race car mechanic told me 250 is OK.

Posted by: Vacca Rabite Aug 14 2012, 08:34 AM

Race car engines get rebuilt every season some times.
Oil pressure drops with temperature. On a race car running WOT the whole time this may not be an issue. But for a street car that goes to idle you may lose pressure.
Some oils break down at higher temps. When the oil can't do it job, the engine will eat itself.

Posted by: aircooledtechguy Aug 14 2012, 09:42 AM

Am IR thermometer works wonders to find if the gauge is giving wrong readings. I recently had a similar problem with my shop car. Gauge was right near red on the freeway. Checked it with an IR thermometer and the taco plate read 212F; PERFECT!! In my case it was a case of using a 911 gauge with an incompatible 914 sender which worked on a different oHms scale.

If it was reading fine before, I would suspect a gauge/ground/sender issue, but without verification by something with a little newer technology, I wouldn't go tearing into stuff too deeply. Check the plugs going into/out of the relay board too.

Posted by: rwilner Aug 14 2012, 11:33 AM

I would suspect the gauge before anything else. To be sure: spend a few bucks on the http://www.mainelycustombydesign.com/engine_components.html and find out what temp you're really running.

Also: I think your 74 is running djet, correct? If so, I believe that ECU knob only effects the mixture at idle...and the ECU will only detect idle if the TPS is calibrated correctly. So, twisting that knob should have no effect on your running temperature I believe.

Posted by: sfrenck Aug 14 2012, 12:43 PM

I swore my timing was right on... 5 mile drive to my friends house, 5 mile drive back and I was overheating. Turned out the distributor clamp bolt wasn't tightened past my "keep it loose enough so I can adjust the timing" amount and I had inadvertently spun it a bit (over advanced) while working on something else in the engine bay.

Reset the timing - no overheating.

Posted by: Dave_Darling Aug 14 2012, 08:59 PM

Some of the stuff in motor oil will break down at 250F. Synthetic oils are less prone to it, but if you run them at 250F for a long time they still won't be happy.

--DD

Posted by: Rand Nov 12 2013, 09:36 PM

Just have to point out, this post has caused a little bit of controversy and I think it should be called out. Not to be an ass, but to clear a misconception.

The 914's fan is driven by the crank, not a belt. There is no "fan belt" on a 914. It is impossible for a belt to affect the fan.

Posted by: Dave_Darling Nov 12 2013, 10:16 PM

Well, if it slipped off and then wound up inside the fan it could block some of the air flow. Like a plastic bag, or a rag...



--DD

Posted by: PanelBilly Nov 12 2013, 10:24 PM

This car has been fixed, but I'll leave the story for Jurgen to tell. I'm guessing he's off working.

Posted by: Rand Nov 12 2013, 10:26 PM

That's a stretch.
Maybe if it was your girlfriends garter belt that got caught in there. They have much more wind resistance.

I had a belt come apart on me on an old Datsun 510 doing about 80. It made such a racket I thought the engine scattered. I discovered the belt separated and pieces of it were flinging around. I trimmed it up with a pocket knife, tightened up what was left and actually made it home on what is truly a "fan belt." Phew.

Posted by: brant Nov 12 2013, 11:23 PM

Race cars don't run over 250.
At least not for long.
That's shut if off numbers