Engine temps

James M · 08-01-1999, 02:22 PM

Ok now that I got my head temp guage what sort of temperatures should my engine be running. I just took it for the first drive here in souther california with the temperature guage in and was getting around 300 to 350, that is about the middle of the guage. Does this temperature sound right or is it to hot. thanks for the help.

aporsche914 · 08-01-1999, 06:44 PM

it sounds good, mine never goes about 350, always under

scriabin · 08-01-1999, 08:27 PM

This question has interested me since first installing a head temp guage in my 71. Mine reads in Celsius, and resides right at 100C (212F) during normal operation, rising only ten more degrees Celsius at maximum--right after high speed interstate driving, having slowed to idle at the nearest traffic light. However, I have removed the deck lid and driven the car with this item missing and noticed the temperature drop even lower, to just under that 100C point, and remaining there during driving (and it is August in Louisiana here). The number sounds low to me, but I have a spanking new 2.2 right now, running on Redline synthetic oil 10-30. I have no other reason to believe the gauge could be reading wrong other than the higher temps I have heard tale of from other 914 owners, and would be glad to hear more from anyone with an oppinion on the matter. Oh, and yeah, the gauge unit and sender came as a package deal, not separate. --john

JP Noonan · 08-01-1999, 08:42 PM

I've always read form Tom Wilson and Bob Hoover (as well as others) how important the gaskets and seals are on an air cooled motor. Are all of you runing all the engine tin gaskets? Some? None? The main ones are the engine compartment seal, then the spark plug holes, oil sender hole, CHT hole. How dirty are the motors, espesially the oil cooler.

Just thought it would be interesting to see how much of a difference the seals make and how a clean motor (clean oil cooler and cylinder fins) makes a difference.

Bill Kohnke · 08-02-1999, 04:10 AM

I have a 70 1.7L but the 96mm pistons installed and the timing is advanced a bit for more performance.
Normal driving gives me around 100 - 150 C
but when I REALLY get into it the temp goes up to around 200 C at the head. But the oil temp gauge in the pan never runs above half way.
The hottest I would that I would dare is 225 C. after that and you probably risk melt down. A couple of years ago I was running a really long hill and section of corners with everything I could get out it, I had the temp up to 250C near the top. At this point the engine started breaking up and running real bad. So I can say that 250C must be the the point where the heads are at their max.
Bill Kohnke

James M · 08-03-1999, 11:46 PM

I am running a 2L that could use a valve adjustment and a tuneup so does what I am getting sound about right. Im i safe running around 175-200 C? Also a couple more questions. where is everyone mounting the sending unit. I have mine at the spark plug and was wondering if mounting it at the temp sensor would give a different reading. And also when the engine is completly cool (sat over night) the guage still points at about 150 does this mean the guage is reading off by about 50 F or is this normal for it not to go all the way down to 100? Thanks again.
James

Joe Bob · Joe Bob's Garage

Two ways to cross check your head temp. If you have an OIL temp gauge with numbers and a matched sender, good OIL temp is about 180 to 220 F. Or you can check oil temp with a hand held pyrometer.

IMHO-Oil and head temp gauges should be used together. If you have the old style oil temp that has no numbers, get rid of it. Spend a few bucks and get a new VDO replacement and sending unit. The senders vary and you need one that is fiited to the gauge. If your gauges are mounted in the center console, you will need a reducer ring. They don't make the odd size gauges anymore. I think the 914 oem gauges were 2 1/8 or 16th. The new ones are 2 inch.

A pyrometer is a handy battery powered unit that reads the temp of any surface with the push of the button. I use mine to check tire temps on race day.

Good Luck.

JP Noonan · 08-04-1999, 02:19 PM

Go to CB Performance page. Mostly beetle stuff but they have a wiring diagram for VDO gauges.

I'm guessing you either have a chafted wire going to the sender (unplug the sender wire see if the gauge goes full left, or lowest reading) or the gauge is bad (most VDO gauges: you groung the sender the gauge goes full right). Does anyone know if ground ing the CHT gauge is the defalt way of testing? I know on my "Bouncy" tach the needle goes all the way right (the way it should) but on the way back stops at 3-4000 and shots up again then to zero. I read in a VDO catlog that the tach should go full right the smoothly back to zero when the sender lead is grounded.

scriabin · 08-04-1999, 02:38 PM

To respond to recent posts, my engine is very clean, and all seals are in place, with the one exception of the hole where my oil pressure sending unit's extension hose comes out. The oil cooler and head fins are free of any oil or debree. And I took the car out to run some high speeds on the interstate today in 98 degree climate--no idea what the heat index must have been with humidity--and maxed out on head temp at 210C. This is a new engine, 2.2 liter, running on redline synthetic 10-30 weight. The head temp sender was purchased with the gauge and is mounted in the original threaded port in the head. --john

scriabin · 08-04-1999, 02:40 PM

Oops, I meant 'I maxed out at 110C' today, not '210C', as I accidentally typed it.