1.2gees - Thermostat change???

PrerYDoG · 03-21-2001, 11:50 AM

Okay, I've gone through history, I plan on changing my thermostat this weekend, and on every message I read I see "I've posted many times how to change the thermostat"

yet, I can't find ANY of those posts...can you repost, or point me in the right direction? Thanks

1.2gees · 1.2gees's Garage

Here's how I'd do it:

Step 1: Loosen the bleeder plug, on the engine block (where the upper radiator hose meets the block/head). Take off the engine coolant drain bolt, and the radiator drain bolt. Disconnect the lower radiator hose, at the waterpump.

Optional: I'd remove the radiator/fan assy, but you don't HAVE to.

Step 2: Remove the snap ring, that holds the thermostat in place, on the waterpump. (evil laugh). Replace the thermostat, and put the C-clip back on.

Optional: Run water throught the block/radiator until you see clear water coming out.

Step 3: Put the radiator drain plug, the engine block drain plug back on. Do NOT tighten the bleeder just yet. Add water at an upper engine openning, the expansion tank is also acceptable, but it'll go slower. (The best way now would be to take off the coupler, where the upper radiator hose meets the block, or add water through the bleeder, otherwise you'll most likely have air in the system, but can be taken out).

Step 4: Start the car, noting the time, keep adding water, as the level goes down, at the bleeder. If the level doesn't go down, you have a stuck thermostat. That's why you should've noted the time you start the car.

Step 5: Get on this board, and curse about the C-clip.

PS: NEVER drain coolant out of an engine that ran for longer than a minute. NEVER change the coolant with a hot engine. NEVER add too much (as in something like HALF) coolant to a hot engine.

I've not done this in over a year, and going by memory here, so if you run into something, make sure to let me know.

My e-mail is "over1g@hotmail.com", and IM name is "over1g".

Hope this helps.
Ahmet

------------------
It's all the driver...

p0r2chby · 03-21-2001, 12:40 PM

Please dispose of your old coolant properly... We lost one of our dogs after she got thirsty and lapped up some of the old coolant I had in my drain pan...

PrerYDoG · 03-21-2001, 12:44 PM

Well, this weekends job is to replace the radiator, the thermoswitch, and the thermostat.

I'm just waiting for Darren at Pelican to return my call.

I'm also planning on getting the Snap Ring Tool...hope that helps with the C-Clip..

but I've seen enough *****ing about it, I'm sure I'll end up adding my 2 cents worth to that.

Thanks.
PS, if you think about it, lemme know if I should do anything else while doing all this.

p0r2chby · 03-21-2001, 01:19 PM

Are you also doing the lower hose.... mine got a little to close too the power steering pump and had a cut in it.

nigel · 03-21-2001, 01:35 PM

Use a genuine Porsche Thermostat!!!! I replaced mine with a copy part, and the temperature never went below 3/4 on the gauge. Fitted a genuine item, and it never went above 1/2!! ( Under normal driving of course)

wolfrpi · 03-21-2001, 01:44 PM

160 degree thermostat from Automotion and a pair of short and slightly curved needle-nose pliers.

Erick

[This message has been edited by wolfrpi (edited 03-21-2001).]

Lawrence Coppari · 03-21-2001, 02:26 PM

I purchased a non Porsche thermostat. Compared it to the old Porsche one and returned it. The flow hole was smaller in diameter. These cars need all the cooling they can get. Bought a Porsche thermostat just like the old one.

Snap On tool will work well I am sure. I used a large pair of offset needle nose pliers ground to fit. Worked well.

Now am changing water pump. Getting thermostat out of pump on workbench is very easy. Hardest thing was loosening the crank shaft pulley bolt.

wolfrpi · 03-21-2001, 02:30 PM

FYI - most likely the hole through the thermostat is larger than the smallest orifice in the cooling system. For this reason the size of the hole is usually of little significance.

Erick

PrerYDoG · 03-21-2001, 02:56 PM

Well, I ordered everything from Pelican today, they're suppossed to call tomorrow when they are ready to ship it, so I won't get to this until NEXT weekend (means I can replace the fuel pump in my Riviera this weekend..pull Gas Tank..OH BOY!!)

I didn't get a low temp Thermostat (Pelican doesn't carry them) You think I should cancel the Thermostat order and get a low temp one from elsewhere? I'm assuming the one from here is genuine Porsche Equipment.

Porsche 951 Fanatic · 03-21-2001, 04:03 PM

FYI - most likely the hole through the thermostat is larger than the smallest
orifice in the cooling system. For this reason the size of the hole is usually of
little significance.

Erick
-------
Yes but there are several small holes in your head, and all that... well a whole bunch of little holes ends up equaling a big one - I could be wrong but does it make sence?

p0r2chby · 03-21-2001, 04:16 PM

Here in CA, it gets hot... I had been running the stock temp switch and thermo and had noticed the car gets a bit warm before the fans kick in. We switched to the lower temp parts and now the car runs cooler and the fans kick in at a lower temp point.

SO, go for the low temp parts... ya have to wait for UPS anyway...

and think about "water-wetter"

Ehab · 03-21-2001, 07:19 PM

Hey PreryDog, I just ordered a low-temp thremo and a low-temp fan switch. Even though I live in cold ass Boston, my engine's temp never goes below 3/4 since my mechanic used a stock thermostat. I got the parts from Performance Products. Both parts with new O-rings cost about $40 with Shipping. Good luck to both of us.

Can anyone explain to me how to pull the C-ring out with a pair of needle-nose pliers??
Ahmet, Thanks for the details.

944slide · 03-21-2001, 11:34 PM

My old thermostat was a 180 F waller, which I believe is the porsche OEM. I replaced it with a 160 F beck-arnley, which seems to work well, with my temp gauge running at 1/4 now, previously it was at 1/2. I think the 160 F temperature is best.

I used the automotion snap ring device, and it worked ok, once the pin tips were securely engaged. I think next time I will try the modified angle needle nose plier technique. I left the fan assembly in place, and while it was not an easy job to perform, it was easier than some other cars on which I have worked.

PrerYDoG · 03-22-2001, 02:38 AM

Thanks for the info guys. I'll prolly cancel the order of the Thermostat from Pelican (they don't have low temp units) and get one of those from somewhere else.

As for the low temp fan switch, I have not seen one of these for a 944 Turbo...I assume everyone who has a low temp fan switch is talking about an N/A 944? Or is there some place I have not looked? (because I've looked hard for one)

Lawrence Coppari · 03-22-2001, 03:02 AM

For each orifice in a flow regime, there is an associated pressure drop. Each and every one contributes to overall resistance and, hence, the amount of coolant flow that can occur for a given pump.

I work for a chemical company. We design piping systems regularly. The situation is analgous to putting resistors in series and amperage that flows.

[This message has been edited by Lawrence Coppari (edited 03-22-2001).]

wolfrpi · 03-22-2001, 06:09 AM

Lawrence - you are indeed correct. I believe the situation is analagous to the formula V=IR. If R is resitance and the thermostat orifice provides this then there will be a voltage drop (pressure?) over the thermostat. In this case though I believe the current (flow rate?) to be pretty small along with the resistance. I think this is due to the speed the waterpump spins at and the restristion that the orifices in the head provide. With the 160 thermostat, at higher speeds in my 951, the temp needle falls below 1/4 if you can believe it!

Erick

Ehab · 03-22-2001, 08:24 AM

But isn't running at 1/4 temp bad? since the engine would probably be over-cooled? I don't know if that is the case, but when I got my 84 944, it had the fan switch shorted, so the fan was on all the time. Additionally, the mechanic told me that the thremostat was always open. My car took a while to heat up (especially in cold weather), but never exceeded the 1/2 temp. According to the mechanic, I was running too cool , i.e. at sub-optimum temps ... so is that good or bad?

Now with a stock thermo and operating fan and fan switch, my car is running at 3/4 to red zone ... which most of you seem to think is 'bad' ... can someone reconcile these thoughts?

I would think that running at a 1/2 would be the best thing to do, but even in the performance parts catalog, they claim that running at 1/4 temp on those 'hot summer days' is a good thing!!!

------------------
Porsche@Harvard

Lawrence Coppari · 03-22-2001, 01:53 PM

Wolfrpi, my 944T would do that - temperature fall off at highway speeds. Did not do this until this winter. So, I took the thermostat out to check it. Thermostat was ok but the gasket behind it was worn out. This permitted a small amount of water to flow at all times. As the pump was old I opted to replace the pump along with the two thermostats. Thing gets put back together this weekend.

nigel · 03-22-2001, 02:30 PM

Running an engine too cold is indeed a bad thing!! The worst situation you could find is that you're constantly running rich, you could even be "washing" the bores with fuel. If the engine is cold, the computer knows it, and sets timing and fueling accordingly. It's also less efficient, therefore worse for your pocket and worse for the environment. If Porsche, with their millions of Marks investment, designed the engine to run at 180 degrees, then thats what it should run at!!