Help! Not cooling!

[balthazar]

I have been driving my 74' 914 for a couple of months now. It's been a long project and I'm happy to be done

I have prolly put 50 miles on it or so. I just got the temp sender working and when I hooked up my temp gauge, OUCH! The engine seems to be running hot!

I have heard some talk about these old VDO gauges reading crazy temps sometimes, so I switched it out with another and got the same HOT readings!

I drove out to a friends house just after installing the center console VDO temp gauge. When I got there, the temp was well into red, but the engine was running fine. I let it get cold and then drove home, carfully. I stopped and let the engine cool each time it heated up. A long process, but I got home

I previously removed the heating hoses, blower and such, so I have plugged up the holes in the tin. The "cooling flaps" mentioned in a previous post are present and seem to be servicable. The tin touches the rubber gasket all around the engine compartment and seems to seal well.

The other thing is that sometimes the temp will drop at idle. (when sitting at a light) when the car is driven, the temp goes back up again

I am going to go over the car tomorrow and see if I can figure this out. Thanks for your help! I know you guys will set me straight!

[Jake Raby]

The engine is either out of tune, or misconfigured- or both. How hot is hot, what instruments are you running and where are they located on the engine?

90% of cooling issues are tuning issues- if that engine is not tuned correctly it will run hot with any system on it!

[John Rogers]

Before you totally panic about the temps, try to get a pyrometer and read what the temp at the sump plate is once the engine gets warm. In the mean time I would pull the oil temp sender and see what the numbers are on it and then pull the oil temp meter to see if they are matched. If they are VDO they have to match up or you will get very abnormal readings. You can check with Pelican Parts or check VDO America's website as they list all the numbers of senders and gauges. Good luck

[balthazar]

The engine is a 1.7L with 40idf webers, 009 dizzy. Asside from the carbs, it is stock. I am measuring head temp with the stock VDO center console gauge.

I took your advice Jake and started from scratch with my setup. I was the guy running 140 mains in my 40 IDFs. I now have 115 mains.

First I timed the engine at 35 degrees btdc at 3200 rpm. I then disassembled the linkage. I put the unisen gauge on the front two barrels and got them matched for airflow. Then I matched each rear barrel to its front.

After that, each mixture screw was lowered until I got an idle of about 900. This is better than before. Now when the vehicle is accelerating, it hesitates or shudders. This happens especially when I first get into gear.

I think it may have fixed the cooling problem, but I can't drive the vehicle long enough to tell. It idles very well. Any ideas?

[Acox914]

OH MAN! the center console gauge is for oil temp! not headtemp!

[John Rogers]

Aron said it........yikes!

[balthazar]

ok...i got that hooked up wrong, but where is the oil temp sender located? I have the "idiot light" sender hooked up to the light on the multi gauge...

I still have a shudder when accelerating, any ideas?

[Acox914]

oil temp sender is located in the "taco plate" on the bottom of the sump. front pass side i believe. a single green wire runs all the way to the console in 73-76 cars. then a switched positive and a ground go to the gauge.

oh john, its "A A R O N" lol

[lmcchesney]

I'm glad things seem to be working out, but, are you sure you hooked the VDO temp gauge to the cylinder head temp. sender? The stock one would be the one feeding your previous ECU. It is a inverted thermistor, meaning the resistance goes down while the temp. goes up.
Another posibility is to pull the sender and gauge and reconnect with the sender in boiling water (220°F) to assure calibration. Or do it in situ.
L. McC

[balthazar]

thanks guys!

Acox914: All of the wires in the car were cut up and spliced in the cars past life. The color codes were not kept. Therefore, I have had to determine what each wire is w/o paying attention to color.. Sometimes I get it wrong :P

lmcchesney: I hooked up the wire which comes out of the right side head near the intake manifold. The wiring on this car has been modified more times than the "truth" at a congressional hearing! I have most of the wires sorted now. I don't have a green wire underneath the engine in the "taco plate"though...!?!?! The engine was made in 1971.

EVERYONE: I now have a shudder, or hesitation when accelerating. I am working on the car all day today to see if I can fix it. The timing is @35 degrees btdc. I had previously balanced the carbs and got an idle around 900.

This is what I'm working on:

1) Mixture is too lean. Would this cause a good idle, but hesitation when accelerating?

2)Spark plugs. Maybe they got fouled when running 140 mains?

3)Ignition setup could have changed. I am going to check this as well.

4)Valve adjustment may be off. It seems like it would not idle well if this were the case, but I will check it as well.

Any other ideas? Thanks a million!!!!!!!!

[balthazar]

Done for the day. Checked all things listed below. I don't know what else to do. Still seeing a studder at acceleration. Now the cars dies and will not start for a while.

1) Mixture - seems to be rich enough.

2)Spark plugs - a little sooty. cleaned up and gap is good.

3)Ignition setup - timing is good and all 4 cylinders are sparking at various rpm's.

4)Valve adjustment - checks out o.k

I don't know what it could be...

[SGB]

"Now when the vehicle is accelerating, it hesitates or shudders. This happens especially when I first get into gear"

Check for slop in the linkage. There is enough wear in mine that I balance to about 2900 rpm, because if I balance to the smoothest "off-idle" transistion, it is unbalanced at higher RPMs. I get the best performance balancing to 3150 or so, but it gets rougher coming off low RPMs in first especially. So thats sumthing else to consider.....

[balthazar]

Good point sgb. The linkage has always been synchronized at ~1000 rpm. An imbalance at higher RPM's could be causing the engine to studder.

I was wondering what range you guys usually have the air/fuel mix screws set at. I have mine set at between 2 1/2 turns and 1 1/2 turns. Maybe this is another area where the Weber tech manual has betrayed me.

Has anyone ever had an ignitor points replacer unit fail on them? Do they typically fail intermittantly or just die with no further operation?

[Jake Raby]

Are you only measuring oil temp?? How about head temps? Oil temps are slow to respond to changes in tuning, head temps can change 200 degrees in 1 mile of driving. Buy a CHT then start trying to figure it out.

[balthazar]

figured it out! One of my carbs had a vacuum leak. This was causing a lean condition. The leak is fixed now. The carbs were a ***** to balance for airflow though.

Actually using the VDO to measure head temp is working well. The needle just barely touch the redline when accelerating hard after warmup. They cool off quickly. Normal operating temp is about 1/2 between redline and zero.

Carbs are now tuned at 2500 rpm. Makes for a great transition. Thanks for the help!

[balthazar]

***I am updating this thread with some content from another, similar thread***

Link:http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/170673-crankcase-vent-tube-carburated-engines.html#post1392818
also:http://forums.pelicanparts.com/porsche-914-914-6-technical-forum/167792-pcv-oil-breather-carb-linkage-s.html#post1392820

update

Well, I just had some more ideas as to what is happening with this setup. My Father and I took the car out for a little spin just now and we made some observations that may explain a little better what is going on here. The pertronix konked out, but that is another story...

The effects are magnified because of the size of my engine. The 1.7 is almost too small for the 40IDF carbs. Even running 115 mains (thanks Jake), there is a very narrow band where AF is correct. I am either too lean or too rich.

Taking the above into account, the added air from the breather on the left side is causing a lean condition at high revs. I was really into the throttle today, and I got a little hesitation at around 5k rpm.

When at lower rpms, say 1500 to 2k, the AF is richer, and the carbs will load up. This is what causes the drop in revs. At idle, the air from the breather drops off, and has no effect on the AF, allowing for a text book idle...

Maybe I'm running headlong into a cam issue here? Perhaps the added lift and duration of a "carb cam" will fix this or at least smooth it out a little, so the "sweet spot" is broader?

[scotty914]

first thing you should try is seeing how far you can throw the 009 dizzy and get a 205a from a 1.8 ljet. the 009 curve comes on too fast and not enough. so by tuning it with 30 degrees ( not what you are ) at idle you might have 20 degrees ( dont know the exact rate of change ) which would make the car seem rich or lean because of more burn time than needed

[Jake Raby]

The problem is the cam.. It only provides 500 RPM of even running witha set of carbs, usually right around peak torque at 3500 RPM... Thats just due to efficiency peaking at that point.