[Cloud9...68]

Starting late last summer, I noticed that my car was running a little warmer than in had in previous years, so when I replaced my belts recently, I also replaced the water pump and thermostat. Also, in the course of my project I ended up taking my radiator out, and found a bunch of debris (mostly dry grass, from a few too many off-track excursions <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" /> ) stuck to it, which I cleaned off, so I had high hopes for the car getting back to its normal operating temperature.



However, it still seems to be running about the same as it was before I did this work. On a typical spring day, with the temperature in the high 70s/low 80s, the needle rests just on top of the 8:00 oclock line when driving on the freeway, and moves off the 8:00 oclock line in traffic. In years past, I seem to remember being able to drive in in the dead of summer in 100 degree central Texas weather, in traffic, and never saw the needle come much above the 8:00 oclock line, so I'm afraid that in its current condition, it would be near the 10:00 oclock line on a really hot day in traffic.



It's not losing a bit of coolant, and I looked at a spark plug recently, and its color was a perfect light tan. The fans are coming on normally, and run for a couple of minutes after turning off the engine, as they always have. Is there anything else I should check before taking the radiator to a shop to have it cleaned out? I suppose I should have the cap pressure tested, but the fact that it's not losing any coolant seems to argue against a problem holding pressure. Any other ideas? Thanks.

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[flash]

yup - cap is a common culprit - each pound of pressure raises the boiling point of water



also, the radiator may be clogged - this is very common when tap water is used - always used distilled or purified water



also, as engines get older, and the compression drops, they tend to run hotter - i suspect it has to do partly with a longer burning fire, due to unburned fuel, and partly due to increased friction of worn components - not sure - could be post hoc ergo propter hoc, but i do know it happens

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[SILVY968]

I have had a heating up problem with a bad cap. Cheap enough to replace. Check to see that there is no air in the system. Run up to operating temp and loosen the bleed screw on the top of the engine to let any air escape. If only fluid comes out you are OK.

Brian

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[Cloud9...68]

[quote name='SILVY968' post='51185' date='Apr 19 2008, 10:53 PM']I have had a heating up problem with a bad cap. Cheap enough to replace. Check to see that there is no air in the system. Run up to operating temp and loosen the bleed screw on the top of the engine to let any air escape. If only fluid comes out you are OK.

Brian[/quote]

Thanks; I'll test my cap pressure today. Speaking of caps, does the car need a Porsche-specific cap, or are these things standard enough that a generic brand will work as well? I'm pretty sure the one in my car isn't an original equipment cap, because it has some sort of a float doohickey attached to a spring attached to its underside. Never seen anything like it before, and looking at the pictures of caps on Paragon's web site, they don't have this float. It's hard to read because of the elaborate font, but the brand of my cap looks like FHP or something like that (could be EHP...), and it's rated to 16 psi. Any recommendations for caps if mine is bad?



And yes, I'll check for air again. I've bled it already, but maybe I didn't get it all out.

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[SILVY968]

I got my cap from Jeff at Sunset. It is OEM. As I recall it was cheap enough that I never bothered to go any further.

The OEM cap is a twist on with no float. What you have is a cap that has a sacrificial metal bar that is supposed to reduce corrosion. I bought one and found that it did not hold pressure after a short time. I trashed it and went OEM.

Brian

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[flash]

pete and i just had this conversation - i think he said 19psi

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[Cloud9...68]

OK, no more "seems" about it... Today was the first really hot day (high 90s) on which I drove the car, and for the first time since I've owned it, the temp gauge hit the 10 oclock line. Here are the relevant facts:



- It started running pretty warm late last summer, with the needle typically at 9 oclock, and getting close to, but never quite hitting, the 10 oclock line. I don't remember ever seeing it above the 8 oclock line before.

- I replaced the water pump and thermostat a couple of months ago as part of my belt change, and also removed a bunch of dry grass and other organic debris from the front of the radiator, and saw absolutely no change - no cooler, but no hotter, either.

- It isn't leaking a molecule of coolant; the coolant level is at the max line on the reservoir, and hasn't budged since I topped it up when I finished the belt job.

- The system is well purged of air. I pressurized it repeatedly, over the course of several days, after the belt job, and I just removed the vent screw today while it was still warm to confirm that there was no air released, and there wasn't, just a dribble of coolant

- I just got my oil analysis results back from Blackstone labs today, and it registered 0.0 for antifreeze content, which, along with the lack of any external leak or change in coolant level, gives me confidence that the problem isn't a leaking head gasket.

- The fans are working perfectly, coming on just as the needle passes the 8 oclock line

- One interesting thing is that, surprisingly, it does better stuck at a traffic light than when it's moving, suggesting there's some sort of airflow obstruction, but I checked, and there's nothing. Apparently, the fans are working heroically to keep the temp in check, but the act of accelerating is heating things up more than the resulting airflow is helping cool things off



- Now, for what I think is the punchline: The top hose (the one running from the radiator just in front of the alternator) is blazing hot, but the lower hose is just lukewarm. This indicates a stuck thermostat, right? It is brand new, but it wouldn't be the first time a new one failed, I suppose.



So, the questions I have are:



1) Does my diagnosis make sense?

2) Is there anything else I should check?

3) Would it make sense to remove the thermostat, and run the car without it, to confirm the thermostat is the problem? As warm as it is right now, I don't think running without the thermostat would be much of a problem. Is there some reason the thermostat needs to be in place in these engines? Thanks.

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[doster]

[quote name='Cloud9...68' post='51199' date='Apr 20 2008, 06:22 AM']Thanks; I'll test my cap pressure today. Speaking of caps, does the car need a Porsche-specific cap, or are these things standard enough that a generic brand will work as well? I'm pretty sure the one in my car isn't an original equipment cap, because it has some sort of a float doohickey attached to a spring attached to its underside. Never seen anything like it before, and looking at the pictures of caps on Paragon's web site, they don't have this float. It's hard to read because of the elaborate font, but the brand of my cap looks like FHP or something like that (could be EHP...), and it's rated to 16 psi. Any recommendations for caps if mine is bad?



And yes, I'll check for air again. I've bled it already, but maybe I didn't get it all out.[/quote]





That's probably a (Rad cap) and the doohickey on the end of the spring is a Magnesium Anode, and it protects the aluminum parts

in the cooling system from electrolysis. I've been using them ever since my aluminum rad in my truck fell apart due to

elecrical current in the cooling system from a bad ground. and am running one in my car right now. Just a little extra peice of mind.

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[banditsc]

Check the connections on the fan resistor pucks, they are located in the battery compartment attached to the firewall. One of mine had corroded connections, the fans both worked, but not quite right and after the fixing those it was much better. Also of course check all the grounds and make sure you have sufficient voltage with the engine and high draw accessories running like the lights and A/C. It really shouldn't dip below 12 volt, mine was low and before it was fixed, it caused a cooling problem for me. Check it with a multimeter at the battery with the engine running and the lights and A/C on.

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[xrad]

Doster: not sure what you mean 'on end of rad cap' there is an overflow tank cap...but it does not touch the antifreeze for the most part.



Cloud 9: thermostats can be put in backwards or can fail when new. suggest replacing thermostat. to test thermostat, run up a pot of clean water on the stove to 190 degrees and place the thermostat into it. should actually see it expand and open the valve. do this before water pump.......also, flush radiator





reduce aluminum corrosion and electrolysis with phosphate free antifreze (and good grounds as stated above)

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[Georges]

Change the thermostat and use a Porsche part. I had problem a couples years back. Changed the thermostat with non Porsche and tested it before putting it in the car. A couple of days later things are back to warm. It turns out the brand new thermostat was failing. Good luck with the cirlce clip with is a pain to get out.

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[Cloud9...68]

[quote name='banditsc' post='53269' date='May 25 2008, 07:56 AM']Check the connections on the fan resistor pucks, they are located in the battery compartment attached to the firewall. One of mine had corroded connections, the fans both worked, but not quite right and after the fixing those it was much better. Also of course check all the grounds and make sure you have sufficient voltage with the engine and high draw accessories running like the lights and A/C. It really shouldn't dip below 12 volt, mine was low and before it was fixed, it caused a cooling problem for me. Check it with a multimeter at the battery with the engine running and the lights and A/C on.[/quote]



Thanks, but the fans are really blowing up a storm, and, as I said (sorry it was buried in my very long post), the car actually does a bit better at a stoplight, when the fans are the only things providing air to the radiator, than when the car is moving, or at least when it's accelerating.

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[Cloud9...68]

[quote name='Georges' post='53278' date='May 25 2008, 10:01 AM']Change the thermostat and use a Porsche part. I had problem a couples years back. Changed the thermostat with non Porsche and tested it before putting it in the car. A couple of days later things are back to warm. It turns out the brand new thermostat was failing. Good luck with the cirlce clip with is a pain to get out.[/quote]



Yeah, that's what I was thinking, too. I'll call Sunset tomorrow (if they're open on Memorial Day), and I think I'll order a new radiator cap while I'm at it. The fact that the lower hose is SO much cooler than the upper one (one of those laser temperature probes would come in realy handy here, but I bet the lower hose is a good fifty degrees cooler than the upper one) tells me it's the thermostat.



When I put the new thermostat into the new water pump, getting the circlip out and back in was a piece of cake, using a pair of 90 degree needle nose pliers. Is it really that much harder in the car? Anybody have any tricks to make it easier? Thanks.

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[Larry Currie]

My car was running a little warm when driving in city with summer heat a few years ago. I changed my fan relay to a voltswagon relay, which I think Flash recommended to me. The gauge stays in the middle now in heavy traffic on a hot Alabama day.

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[banditsc]

[quote name='Cloud9...68' post='53281' date='May 25 2008, 11:53 AM']Thanks, but the fans are really blowing up a storm, and, as I said (sorry it was buried in my very long post), the car actually does a bit better at a stoplight, when the fans are the only things providing air to the radiator, than when the car is moving, or at least when it's accelerating.[/quote]



I had the same issue, it would run hot while at speed but cool down when I got into traffic, it was very strange, it also ran warmer at night when I had the lights on, (high electrical load). My fans also seemed like they were blowing strong, but I found one of them had corroded terminals to it's resistor pack, so it wasn't blowing as it should.

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[Cloud9...68]

[quote name='banditsc' post='53285' date='May 25 2008, 12:10 PM']I had the same issue, it would run hot while at speed but cool down when I got into traffic, it was very strange, it also ran warmer at night when I had the lights on, (high electrical load). My fans also seemed like they were blowing strong, but I found one of them had corroded terminals to it's resistor pack, so it wasn't blowing as it should.[/quote]



OK, I'll check the terminals. One other clue I forgot to mention that I think points to the thermostat, though. When it got so hot yesterday, I turned off the AC, and tried turning on the heater, and - nothing. No hot air blowing out of the vents whatsoever. It looks like the bypass to the heater is downstream of the thermostat, so it would make sense that the heater wouldn't work if the thermostat were stuck. It's strange, because I ran the heater full blast after replacing the belts/water pump/thermostat, and it worked just fine, so if it's really the thermostat that's the problem, it's gone bad just a few weeks after installing it.



Thanks again for all the suggestions; as usual, hopefully this discussion will help others as well.

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[xrad]

I posted this pic earlier.....easy to make circlip tool...worked like a charm....BUT, the clip has to oriented with the two holes towards the rear of the car to make it easy!

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[Cloud9...68]

Ah, so you bent the plier tips about 45 degrees. Looks like a very good approach. I don't have access to a torch to allow the bending of my 90 degree pliers, so I guess I'll be struggling a little. I'll see if I can get the circlip turned so the two holes are pointing toward the rear of the car. Thanks for the suggestion.

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[xrad]

if you have a local hardware store or home depot, they sell MAPP gas and a torch kit for about 20$ looks just like a propane torch but uses MAPP gas (YELLOW CAN) to create temps well in excess of 1000F. dunk tips in water after bending to keep molecules somewhat aligned and the tips fairly hard.



ALSO: Note that I ground the tips so that they will fit into the clip holes.....

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[flash]

cooling system tip of the day - do NOT use tap water to fill your radiator - distilled or de-ionized water only

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