New 73.5 owner needs advice/help/to be shot

Deschodt · 08:18 AM

Guys,

Merry Xmas... I hate to bother people today but... My gift to myself was a 73.5 T which I bought from across the country, sight unseen, after a family member inspected it for me. He did a good job on the body, but mechanically I am afraid ¨we¨ missed stuff... I say "we" because I should know better than to buy a 911 sight unseen....

Anyway, it's not all bad ! The good...I got me a 99.7% rust free "long hood" of undescribeable color (see below) with S options, factory AC, a nice interior and an original 2.4 CIS engine...The gearbox is also pretty sweet, better than my 83 was!!! Never thought a 915 could be so smooth ! And I paid a shade over 11K...Not bad I think as those cars don´t grow on trees anymore..

The bad... The engine started and ran well with the choke (it´s a 73.5 with CIS remember).... Once the "new car giddiness" wore off I quickly noticed the oil level gauge pegged to full (I assume a bad ground because there is oil). Strike one... The temps gauge does not even seem connected, it never moved as I drove the car back to my base camp. That's Two.. Strike 3: The oil pressure seems awfully low 25/45- that is where I am freaking out - it is supposed to have passed a PPi with good compression. 4:it does not hold
idle worth a **** when warm apparently, fully exercising my heel and toe capabilities.... It wants to die and will buck and fart when prodded back to life...

Back to the oil pressure. I thought I knew 911s on account of having owned an SC and a 993... Guess not! What on earth is this pressure gauge showing? My SC had 0-5 bar (0 to 70 PSI more or less), this one seems to be in PSI, 0 to 140. But 140 what? If PSI, that's 10 bar, is this even possible that Porsche halved the gauge reading on subsequent engines?

Anyway, it never ran above 45 on that gauge, that was at 4000 rpm, and as it warmed up it progressively got a lot closer to 25 still at 3500/4000 rpm, practically 0 at idle (when it held idle which was not often). What measurements am I reading? If PSi, aren't they low? Am I gonna have to buy a 3.0 sooner than expected ? ;-)

While I am humiliating myself here, where on earth is the oil pressure light? the oil instruments have temps, pressure, and there are 2 idiot lights, once for the handbrake (even that one's flaky and came on and off at times) the other says G, which I assume is generator or electrical. (That one stayed off..)

Now what's odd is that on the road, in motion, the engine runs very strongly, not at all like an engine about to grenade... not a crisp response to sharp gas pedal movement but I assume that is 73.5 CIS at work, but it pulls very well !

Can those gauges-senders lie that way? Showing low pressure ? I kinda doubt it... I know better... Argh.. Opinions ?

Other minor niggles, the steering wheel is cocked, brakes will need work as it pulls left (my 356 pulls right, we're even), but the body is superb... So what's the consensus ? Will the engine lunch itself while I am on my way to the transporter that'll take her home, or once it gets home? ;-)

Last Q: No owners manual :can I raise the idle by turning that big
screw behind the airbox? Thanks guys!

Greg . Freaking out in Berkeley, far from home about 25/30psi at 3500/4000 !

randywebb · 12-25-2004, 02:59 PM

The oil pressure sounds problematical. You have an SC so you did check the oil properly? Have you changed it yet? If not, do so. I sounds like it is a bit low. What does it read at 4,000 rpm after being warmed up?

The tank oil level gauges are often bad. Check the sender first and do a search to find tips.

A rust-free early car is a good thing to have. The price is a bargain if the only problems are minor ones.

Elombard · 12-25-2004, 03:15 PM

I have the same car - maine already had a 3.0 in it when I bought.

No idiot light. The b is for the e- barake, should flash when engaged. I added an idiot light, easy on the sc motor because it has the sender. I dont believe yours does.

If the oil tank 'harness" gets unplugged it pegs like that. Mine gets unplugged at the through the body plug at the passenger side rear of the engine compartment. Usually easiest to mess with from underneath.

Deschodt · 06:12 PM

Thanks guys.. Keep'em coming !

Can anyone confirm the gauge readings ? Is this supposed to be 0-140 psi ? I can't believe it would go so high and the follwing cars 1/2 the scale!

Here it is by the way:

Elombard · 12-25-2004, 03:23 PM

Mine runs about 90 psi cold and 50 or so warm I think . I beleive that is PSi, I always assumed it was. I dont think 100 PSI is unreasonable in a car motor is it??

randywebb · 12-25-2004, 03:55 PM

Wow! Great color. When you get the problems addressed, you con do some improvements like tossing the rubber bumperettes for the chrome ones with a thin rubber strip on them.

I thin it is in psi. I have a '73.5 but never had the origianl engine - so am not sure what your readings ought to be - usually, 10 at idle and 10 more for each 1,000 rpm.s is what Bruce Anderson said in his book.

Also replace the rubber brake hoses soon and flush - add a new quality fluid - Motul, Ate, etc.

Change the trans oil.

724doorE · 12-25-2004, 04:04 PM

Ditto what the rest have said, 50-60 psi at 4000rpm and these early cars are known for the gages to read low like 10 or less at idle when warm. There is also an orifice you can put in to restrict the flow to the cam supply which is where the gage reads that will raise the pressure you read. Do a search on that, pelican sells the restrictor too. The gages on my 72's will peg when cold until warm if you get on it. I have had the oil bypass mod done though. Good luck Is that Auburgine?

looks good!

Shuie · 12-25-2004, 04:06 PM

Stop freaking out. You have a great looking car in a great color!

Wayne 962 · Wayne 962's Garage

Wow, if those are the biggest problems, then you did just fine.

If you check the owner's manual of your car, you will see a note in there (maybe not listed in the 1973.5 manual) about how the low oil pressure light may go on when the car is hot and at idle, and pressure may read zero. Very normal. Freak-out for new owners, but normal...

-Wayne

Jim Sims · 12-25-2004, 04:28 PM

My son and I have done a full restoration of his 1973.5 911T. Almost all the "problems" you list appear minor or are nominal readings (oil pressure readings are in psi) for this car/engine. The warm idle problem could be the most expensive if it is being caused by a defective WUR but there are other possibilities such a leaking cold start valve or that the CSV OEM wiring has been "messed with" and it remains on whenever the start lever is pulled up. A clogged return line from the fuel distributor to the fuel tank could also be a possible cause. Before doing anything, the timing and dwell should be checked (if points are still installed) and the CIS system pressures checked with a CIS test rig. Do not let a mechanic try and solve the problems by "throwing parts at them" as this can become very expensive in a hurry. Given the age of the car I would recommend that all the hoses in the fuel and air (vacuum) system (engine, up by the fuel tank and in back by the fuel pump) be replaced. What oil is in the engine; for Berkeley, CA a 20w50 should be installed. Lower viscosity oils will result in low oil pressures when warm. Cheers, Jim

Deschodt · 06:17 PM

>Wow, if those are the biggest problems, then you did just fine.

Wayne,
Thanks for the reply. I don't have the manual but i did order one from you guys ;-) If there is a low oil pressure light on my car, I have no idea where, there are only 2 lights on the pressure gauge I can see, one for the handbrake and one for the electrics...

To be clear - I am not freaking out about a 0 reading at idle, I am freaking out about 25/30 PSI reading at 3500 rpm when warm. And the fact it does not hold idle, but much more the low pressure... There is no way I am seing 50-60 PSi at 4000 like people have mentioned. also no way I see pressure pregged when cold.... I've never gotten close to 60 which is not even 1/2 way up the gauge, maybe except upon startup but i don't want to rev it hard while cold either..

Jim,
thanks, sounds comforting if it's just the oil, I have no idea what oil is in there now, I will replace it upon arrival of the car to my home - I am shipping it back to Florida the day after tomorrow... I am not very worried about the oil level or temps gauges, i own a 356 I know how to fix those, it's just that with those 2 dead + low reading on the pressure gauge, I had very little info to go on when I drove the car back and was worried it was gonna grenade itself;-) I still think it's too low, but we'll see...

Short term: Can I raise the idle a bit or should I leave the "choke" on so I don't have to heel and toe at every traffic light ? ;-)

Other comments: yeah randy, the front bumperettes are already gone and I like the chromed ones for the back. I also have a set of pelican ordered Chromes trim ring H4s awaiting installation as it currently has the fugly US sealed beams...

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Deschodt
To be clear - I am not freaking out about a 0 reading at idle, I am freaking out about 25/30 PSI reading at 3500 rpm when warm. And the fact it does not hold idle, but much more the low pressure... There is no way I am seing 50-60 PSi at 4000 like people have mentioned. also no way I see pressure pregged when cold.... I've never gotten close to 60 which is not even 1/2 way up the gauge, maybe except upon startup but i don't want to rev it hard while cold either..

Get yourself a copy of 101 Projects (www.101projects.com). In there I talk about the oil pressure sending unit, and how it's notoriously unreliable. You should replace this first before you start to worry. Ever taken one apart? The insides sort of resemble an old tube radio - lots of 30-year old technology in there...

-Wayne

LakeCleElum · 08:38 PM

Looks like a great score there. I have a '73.5T and confirm your oil reading are normal. If you're having a problem with idling when warm, I don't think that is the WUR. That's good news as they cost over $400 with the conversion kit. Your CIS is very senititivbe to water and dirt in the fuel system. I would replace the fuel filter, put in some additive to absorb water in the fuel and start driving home. If it don't idle after a few tanks, have the CIS checked. Sysem is likely dirty.....Great looking car....Bob S.

Deschodt · 12-25-2004, 07:29 PM

Phew, thanks guys, I feel better....
Wayne, I already ordered the 101 projects as well as the owners manual ;-) Just have not received it yet..
LakeCleElum, that is good to hear.... Sounds awfully low to me (and silly as those readings use 25% of the gauge) but I'll take your word for it, I wanted to hear good news ;-)

Thanks guys, happy holidays !!!

HarryD · 10:22 PM

Hi:

Congrats on getting (what I think) is the best of the streetable long hoods. But then again I am biased as I have a 73.5 also. Great color too. One of my all time favorites.

I think most of the isues you raised have been addressed but I wish to add to the "party".

Oil Level-Check the wiring. I haven’t had this problem so I haven't looked into it too much. Not to worry, just use the dipstick each time you fill up. FWIW, contrary to what others say, my gauge and dipstick agree pretty well so once you get it working, see if it is useful to you as well.

Oil Temperature-Check the wiring. The transmitter for temperature is to the left of the fan and is the small one. The large unit is the pressure transmitter. Unlike our brethren with a later models, these devices are where we can see them!

Oil Pressure-The gauge is calibrated 0-140 psi. On start-up I show 40-60 psi and as the car warms up, the idling pressure drops until it is unreadable at full temperature. When warmed up I see about 10 psi/1000 rpm. There is no lo pressure light on our car. Our host has been kind enough to post our wiring diagrams in the Tech section of the parts store (http://www.pelicanparts.com/911/911_Parts/911_electrical_diagrams.htm). You might find it helpful.

Idle-Check for vacuum leaks. Does it surge or just die? If you set the hand throttle at about 1200-1500 rpm, does is hold, surge or die? You can leave the hand throttle up, it is NOT a choke. It does two things: when you crank the car, it turns on the cold start injector to squirt an extra bit of fuel into the car to help it start and to hold the throttle plate open to raise the idle speed as it warms up. After you confirm no vacuum leaks, you may need a mixture adjustment. My car surged quite a bit until I got the mixture right. Save yourself some aggravation and bring it to a shop with a CO sniffer and have it adjusted to spec.

Anyway, you may be better off than you think.

Deschodt · 08:28 AM

bump - just in case someone else can confirm the pressures - that'd make my Xmas ;-) Thanks guys !

Oh and someone keyed the driver door overnight. nice... Don't even know anybody here... not the best start ;-(

Jim Sims · 12-26-2004, 08:35 AM

Oil pressure is normal for this year and engine and miles.
Did you leave a 911 parked on the street overnight in Bezerkeley?

Jim

randywebb · 12-26-2004, 11:01 AM

One tidbit, one post above suggests you live in FL - so adjust Jim's oil viscosity rec's for the temperature there. Probably the same as for Bezerkekley right now.

Sorry to hear about the door. Be careful where you leave a nice shiny car parked - even an old one. If the pigment color can still be seen in the scratch, then Meguiar's Scratch-X may conceal it.

Sunroof · 12-26-2004, 06:18 PM

Relax.
I have owned my 73.5T with CIS and the 2.4 for over five years now. The engine was totally rebuilt, every CIS component replaced besides the fuel distributor and it leaks no oil. Here is what I experience.

What you are seeing on your guages is normal. I never see my oil pressure gauge go above 60-70 even when stone cold or in the heat of summer. I have always known that the rule was for every 1,000 RPM figure 10 on the oil bar. Red line at 6,000 and your at 60-70 on your oil gauge. As for the oil tank level gauge. Most bounce around like something was a-miss, but they seem to settle down after awhile and indeed attempt to show you the oil tank level concurrent with the gauge.
Easy to check the oil level on your gauge with the dipstick reading
Your in the limits..............

Some suggestions from one 73.5T owner to another:

Add 3-5 ounces of Marvel Mystery Oil every two or three fillups to the gas. Great for better lubrication the top end.
Use SWEPCO in the 915...big shift improvement.
Double check your ground strap from the tranny to the body/engine. Make sure its all clean.
Make sure your hand throttle is working satisfactory. LIFE IS BETTER WITH THAT HAND THROTTLE!
The cooler collar will take a needles worth of heat off the gauge as well as the heat sheets. Good added insurance. The 2.4 is not known for over heating. With AC blasting in the Atlanta summers, its stays below 220.
I use Valvoline 20-50 Racing and its great, but everyone has their favorites.

Its a beautiful machine that will give you years of pleasure. Congradulations.

Bob
73.5T

Deschodt · 12-28-2004, 11:34 AM

Thanks all !! Yesterday I drove the car to my old mechanic (one of the few reasons I miss the bay area) for him to investigate the Warm idle (or lack thereof - thank goodness for the hand throttle in traffic) and CIS issues in general... It's in good hands. I suppose at some price point it makes sense to go to carbs, but I am not there yet..

I saw 90 psi last night when starting her up bone cold, and that gradually went down to 30 or so at 3000 rpm, so I feel a bit better about the oil pressure. I guess the good doctor must have laughed in his grave "ya, ve put ze 140 psi gauge on purpoze for you to vorry, all meazurements occur in the 0-50 range" ;-)

As for the $#$$% who keyed the door, what can you do. I have never thought I'd be on the receiving end of that, especially in a classic car and away from home, but what goes around comes around... I'll see if I repaint the door or the car - the paint looks great on the digital picture but it's actually a so-so respray upclose - no great loss there... just irritating... I kinda liked the color but if I repaint it, for my money I'll probably change it... ( i already have a weird colored 356, one's enough)

I appreciate all your help !!! I hope I can return the favor someday !

Greg.
73.5 T (pulls left under braking)
57 A (pulls right under braking)
Brake jobs looming !