Newbie Questions

Cobey SChmidt · 03-23-2003, 07:50 PM

Hey all! I recently purchsed a '79 928 that needed some work and have a few questions. I'll give you the run down first. (Sorry if I am a little lengthy.)

One of the problems the car has was that is was getting VERY hot. Right up almost to the red mark. Perhaps it would have gotten higher but the PO would shut if off at that point. Everything he told me led me to believe the thermostat was dead. So, I ordered one online. ($23 shipped!) What I got was a Wahler 4105.83D and the O-Ring.

I went and made the switch today. The old on was pretty well jammed in there, and just getting the old O-ring off was a challange. Once off, I noticed the original was slightly larger than the one I got. When I put the new one in, it had a lot of play in the socket. Also, there seemed to be no coolant anywhere to be seen. The instructions I had been following mentioned that I should -- especially since I hadn't drained the radiator. I tightened everything down pretty snug, though no so much that I worried the bolts would snap.

I fired it up. The engine heated up, but not quite as hot. (Joy!) I turned on the heater to see if the temp out come down a bit more. No heat. None. The blowers were all on, but no heat came from the vents.

Out of curosity, I thought about there being no coolant and asked the PO when the last time he had put any coolant in and what type. I got a vague answer about something that cost a lot ($13) and it was when the problem first started. With that, I started adding mroe coolant. After the third jug, coolant started coming out from the housing there the thermostat resides.

I thought I must have not tightened everything down as wel as I thought, so I took it all apart again. I made a nice mess, then put it all back together again, making sure to tighten it best as I cold. This time the leak was much smaller, and the engne ran even cooler. (Imagine that!)

Now for my questions.

1.) Is the Wahler part I got the correct one to be using? The instructions I had dictated a different part number, and the fit seems to be a problem (or I am a total idiot).

2.) The no heat thing bothers me. Any pointers on where I should start looking?

Thanks!

AFJuvat · 02:49 AM

Ahhhh welcome to the joys of 928 ownership (otherwise known as "Oh my god, you want how much to fix it!?")

Wrong thermostat - replace with a stock part. Part number 928.106.129.06

Sounds like your PO ran the engine without coolant or very low coolant - that does not bode well on an all aluminum engine.

Where is the coolant leaking from? You will have to locate the source of the leak.

You still need to add coolant to the motor, the air should purge itself out in time - keep filling.

AFJuvat

Cobey SChmidt · 03-24-2003, 05:29 AM

Someone replied! LOL.

Yes, this is going to be one of those cars that sits in a garage and gets tinkered with as time and money permits. I already bought the 9 vol. manual set, but it isn't as helpful as a human expert in some areas.

The leak is coming right from the seam between the thermostat housing and the thermostat housing cover. Obviously, the o-ring is not sealing correctly.

AFJuvat · 03-24-2003, 05:55 AM

Yep, definately replace.

No heat is probably caused by an air bubble in the heater core - air gets trapped there. It should work itself our with lots of coolant and time - you can fill the system as much as you can and then pressurize the system with an air source to get the air out - run the heat when you are filling.

AFJuvat

Cobey SChmidt · 03-24-2003, 06:36 AM

Thanks!

A bit more reading and I surmised the lack of heat was probably becauseofthe low coolant level (no coolant getting to the heater core). From what I had read, once I add coolant, I should run the engine with the radiator cap off and the heater on. Then, add more coolant as needed. Correct?

Now for another newbie question...

I have never had a car with an oil pressure gauge. What is the "proper" operation of this instrument? While the car is idliing in neutral, I see it sit at about the middle of the spectrum. When I give it some gas, the needle jumps up to the top point. I know it needs and oil change (I'm going to give it one regardless), but I don't know if what I am seeing is normal or not.

Thanks!

AFJuvat · 03-24-2003, 08:33 AM

Yes, the oil gauge is normal - oil pressure under load should stay between 4 and 5 "bar" on the gauge.

can drop to 1.5 with the car at idle.

You got the coolant correct as well.

AFJuvat

Cobey SChmidt · 03-24-2003, 08:34 AM

THANKS!!!!

cas · 04-03-2003, 12:36 PM

ok,wait a second and let's do this right.first of all get the right o-ring and thermostat,even if that's not the problem it's a question of maintenence.now run the engine to operating temp.turn on the ac.the electric fan in front of the condencer should go on.now turn ac off,fan should go off.run engine till hot fan should go back on,if it dosn't ,you need a new low temp fan switch.when the engine overheats at low rpm,the belt driven fan isn't spinning fast enough to cool the engine so the electric fan should come back on. the fan switch is located on the driver side radiator end cap close to the bottom.it looks like a o2 sensor.drain the radiator first. now for your heating problem.there are three major components to check.first the blower,we allready know that works.second,the heat transfer flap.remove the driver side interior shelve,look under the dash for a small black box about 2" x 2" with a small arm.with car running slide climate controll button to full heat,arm on box should move up and down opening and cloaing flap for hot and cold.give it a second,it's vacume actuated not a light switch.now pull off your air cleaner box. close to the fire wall you'll see a vacume controll unit with a in line valve conected to a heater core line.with the heat on the vacume should open the valve,if not,turn it with your fingure or a pair of vise grips letting warm coolant to the heater core.air?i don't think so,the return line from the heater core is on top,water is dencer than air so the air will wind up in your tank on top so save your motrin,i'm glad to help and advise ia allways free. cas.

Cobey SChmidt · 04-03-2003, 12:49 PM

Thanks cas!

I did replace the thermostat, again. Fools sent the wrong one.

Now, on the fan checkout. Will the front fan activate even if the hood is open? I understand there is a sensor somewhere what will deactive the fan if the hood is open. (Need to find that guy.)

cas · 04-03-2003, 09:48 PM

any sensor in the hood is the factory alarm.be careful,theres a tag on the fan housing stating the fan starts automatically.this is proof the fan will run with the hood open or closed.also,if it's cost effective,just replace the fan switch,also a maintanence issue.don't forget pipe dope.now,that guy?loose him.i've been a certified mechanic since 1979,if i don't know,i'll say i don't know however,if isay i do know, it's because i do. get to the heat,i'm curious to know the problem. cas.