pugface

Hi guys

I've been searching the archives, and coolant temp comes up pretty often. But I've read so many old threads with different questions and opinions, that I thought I'd start a fresh one, if you don't mind. Forgive my lack of DIY skills and knowledge, but I'm trying to learn!

My 1986 NA seems to be running hot, particularly at idle. Temp creeps up to, and even just above the third mark. Temps here are in the upper 90's, and will be that way for quite a while, and it is making me paranoid to take the car anywhere where I might get stuck in traffic, or stoplight to stoplight.

I don't think this is normal, at least to this particular car, but my timeline makes that a little hard to prove.

Nov 2014 - bought the car, drove it as a DD in Chicago. Obviously, the outside temperatures were much colder then, but it always ran cool
Apr 2015 - drove the car to Texas in preparation for a move, and put it in storage. This is the first time it started running hot (but didn't overheat) - thermoswitch went out. Thanks to Rennlist, I found the A/C button trick to run the fans, and it stayed cool after that.
Jul 2015 on - Drove the car sparingly as I procrastinated with the thermoswitch, always stayed cool with the A/C fans on
Jan 2016 - Finally decided that I wasn't going to work up the time nor courage to change the timing belts myself, had full belts/rollers/seals/water pump/thermostat/thermoswitch service done by a reputable shop in San Antonio. On the way home is the first time I noticed it running hotter than normal. Where it used to go between 1/3 and 1/2 the way past mark 2, it was getting awfully close to the third mark. I called the mechanic when I got home, and he said "they all do that".

I tried to be reassured by that, but as time goes on, I am not. I have been researching, and I have done the following:

Bought a new expansion tank cap - no difference

Read about air bubbles and bleeding the system - I've tried elevating the front end and bleeding, and I bought a Stant pressure tester and bled it using that twice. I don't really see bubble when I bleed, just a gush. The first time I did it, the upper radiator hose was mushy, like it wasn't completely full of water. Squeezing it seemed to force air somewhere. Hose feels solid now. The bleeding seems to be helping, as the heating seems to be more sporadic now? Maybe. I drove it today to get the mail - left it idling while I picked up the mail, gauge went to 3/4 or 7/8 to the third mark. Gauge came down on the way home, and I let it idle in my driveway while I checked some things, and the gauge stayed at 1/2!

A few more things which may or may not be relevant:
I have a Harbor Freight IR thermometer, for what its worth. I'm seeing maybe 195 on the upper hose, and 180 on the lower hose. Any spots I should be measuring?
I'm not getting heat from the heater by turning the climate control up - but when I turn on defrost, I get it! Unpleasant when the outside temp is 98 to start with
New thermoswitch seems to work, my high speed fans run about two minutes after shut-off

I'm happy to do my own work when I can, but I'm going back to the shop this Friday to get the A/C fixed (hopefully). Anything I should ask them? Any possibility I just a a bad replacement pump or thermostat?

Thanks
pf

odurandina

too many bazillion threads (like 3000 threads) of hot motors including my own to count.

it's always usually about the same.... hot air trapped at the top of the engine.... steam rises.....

just kills the damn thing .....slow death spiral

speeds up aging process

time passes, just gets more hot new h20 pump maybe helps sorta...

gets hot anyway wtf why ? why God???

speeds up the aging process faster.....

and it's a slow or less slow death spiral.

my 968 blew a hg MASSIVE.... i fixed with sealer bfd...LOOK MOM NO WRENCHING!......

i was at a gd autozone on a long transcon for crissakes.

kinda f_cking great....

10 or 12 k miles later like 4 months, it started back running a little bit hot in traffic on hot days but didn't do that before.

why God why?

could never get that top part of the engine air bubble out.

a few months later ran a little warmer. kept adding coolant..... just kept coming back sorta.

2nd blue Devil treatment at about 180 k miles (about 24 k miles after the first time).

effing Porsche crap engineering plus 4 banger laws of physics and old sh_t getting more old and crappy.

every few thousand miles, it ran a bit more hot.... then it got to not even liking to sit idling in traffic.

still i got a bit over 50 k miles more out of her with 2 hg treatments w/ that big angry motor.

like 52 k miles free!! that hg sealer made my engine run great again sorta.

she never ran cool again after the head gasket started going..... but she got pulled and went to a new home.

still hardly burned a drop of oil like a third of a half quart every 10 or 12 k miles.

but it was an interesting 52,000 wtf miles. my death spiral was much slower than the usual 944 garbage you read about.

installer pulled that gd thing at 200k and i got 1 more helper on it who worked out the rough edges the guy who builds free houses for the poor in st lucia in the bahamas or some sh_t tropical place.

got that v8 and never looked back.

anyway, they delivered the bomb............

LS life is bad ***. gd car sounds exactly like the GT40 that won La Mans. a raging steed out of the apocalypse.

when the 4 banger sh_t gets hot, it's a slow death.

check your h20 pump..... when that's checked down, get out the fluid

change to water..... put in blue devil...... keep the water in for a bit.... flush.......

swap up a new radiator....back to coolant.........

when that air bubble comes back repeat spin cycle circle of life in your **** 4 banger world.

enjoy.

(it's a slow death).

odurandina

i repeated the part i read in your post above here.....

but this; "They all do that"

you must be a long lost cousin or something.

yes soldier,

they all do that.

944Ross

I'm in a similarly hot location, and if I'm understanding your descriptions, it's exactly how mine is. The fans come on at the 3rd mark (3/4 of way to Hot), with the A/C off. So if you're sitting at a long stoplight, the temp is going to creep up to that. There is a hill on my way home, a 6% grade, that I hold 4th @ 2500 - 2700 RPM on the way up. It will send the temps up to where the fans kick in by the time I'm at the top; then the fans come on, and it cools back down.

I had an '84 that was the same way, relatively. I don't think it's abnormal, and sure doesn't seem to hurt anything.

divil

Does turning on the AC switch the way you did before still keep the temp down the way it did before, in the same weather conditions? If so, then I think that points to everything being fine. You moved to a hotter location - it ran hotter. You cooled it artificially (with the AC switch) - this probably resulted in the fans running at times that they would ordinarily not, so it actually ran cooler than it typically would in your new climate. Now you are not using the AC switch any more, so it's back to running the way it should for this climate. The reason for the confusion is because 2 things changed at once: you moved to a hotter place and your thermo switch went out. Fixing just one of those things (the thermoswitch) is not going to get you back to the way things were before.

Aside from that, my experience has been that it's pretty normal for it to get right up to the top white mark in hot weather when sitting still. What I've heard is that modern cars filter out the short term changes and show you an average temp, which is why they appear to be rock solid. The 944 doesn't do this so you see the natural fluctuations on the gauge. I don't know if that's true but it certainly makes sense from what I've seen.

Arominus

Replace that thermoswitch, also it is not unusual to see the temp move between 1/3 and 2/3 on the gauge depending on the load even with the fans on full blast. I saw close to 2/3rds on an uphill grind @ 75 in the nevada desert with the A/C on in 106 degree weather while road tripping last year. Which is normal because its hot out, the motors working harder and the A/C is dumping heat in the rad. Its going to be warmer.

The temp gauge is not dampened like it is in newer cars, so you see more movement out of it.

odonnell

I live in southern TX and with 1 radiator fan installed, I never go above 1/2. That's with a low temp thermostat and fan programmed to come on at 185* F.

pugface

Hey, OD told me to put a LS in it! Now I feel like an official Rennlister

I'm not anti-swap - I used to own the car the SBC should be in - a Jaguar Xj6. It threw a rod through the oil pan.

Anyway, I can see situations where it makes sense, but not for me. I just want a stock, well-maintained 944 for an occasional drive through the hills to the liquor store

pugface

Ran some errands today

The car came up to temp (1/3 past second mark) in less than 2 miles at 45 mph
Ran cool into town, at a few lights I'd notice it slowly creeping up to 1/2, then back down as I moved along, which is what I'd expect.

After some stops, when I first started the car, it would shoot up to the third mark as I was leaving the parking lot.

Seems sporadic - I understand it will raise at idle, but sometimes it goes further than other times. This time, it did shoot up to 7/8 when I idled by my garage for 10 minutes or so, but stayed steady there. I took some pictures of readings, but evidently my phone is having the same problem - the battery is all swelled up, so I need to wait for Amazon Prime to get those!

I went through the PCA tech archives, they mention several times to carry 1 12mm wrench for a week to bleed after every trip, so I'll keep doing that.

I will check the fan relay by Clark's garage method in the morning to verify both fan speeds are working.

Thanks
pf

odurandina

i hear you. it's a huge decision (but just wait til you see my next post, by God)..... people posting the numbers they post must be seriously great fabricators and wrenchers. you ALL have my respect - but i honestly wouldn't attempt a swap unless i was either at an elite level, like TechnoDuck, Van or others - or if i had at least $25 k to put into the swap before changing the transmission and beefing the suspension. I would attempt to find an engine that could be fully "swap dressed" with 944/LS oilpan, headers, etc.... and still stay within, sa $6~7k engine. I spent close to $30 k on my engine, dressing it for the swap and transmission. where the rest of the cash went was mostly in swap parts, labor - and for refinement...... yes.... the money, your time (or someone elses), goes fast. there are many things to do - and they need to be done right.

then you get to changing the gearing in the transaxle, sorting the suspension, adding bigger brakes, and better wheels and tires.

mrgreenjeans

" the mechanic said ...... They All do That "

No, they don't. And good running , well maintained cars do NOT have heating/cooling issues.

IF,

-all the grounds are clean
-the switchgear is turning on when it should for temp control
-the wiring hasn't become ensnared in the fans and gotten cut, then retaped with gaffer tape and now it's ''good to go''
-the dash gauge is working and indicating correctly
-there is no air lock in the cooling system
-there is no aluminum flakes clogging the heater core or filling the water jacket
-there is a proper Wahler thermostat that flows correct volume and regulates opening and closing correctly
-there is a properly rebuilt OR a new Porsche water pump flowing correct volume
-there is a proper thermo fan switch with a low coolant temp sensor for cooler running
-there is not a head gasket failure issue
-there is not a clogged radiator core internally--- from galvanic corrosion due to improper anti-freeze
-there is not a clogged radiator core externally--- from bugs, dirt, and leaves/seeds
-there is a properly operating BEHR radiator cap
-ALL air locks have been properly purged ( nose up, bleed sequence followed, air burped with heater core opened
-both fans are kicking on when they should and operate in tandem at peak temp

Too many folks have improperly cared for and non- maintained cars, needing to be serviced by proper 4 cylinder Porsche mechanics , not unfamiliar with the nuances of the 944, 951, 968, 924, 924S, and 931.

They go to hacks familiar with American or Japanese makes or think it's just a 'Porsh', taking their learning as they go by reading online.

Reread as much as possible here on the R/L pages about cooling issues. Clark's Garage, 944Online Forum, and your Haynes and Bentley manuals. The Porsche Service books available online or in print........
there isn't any reason to forego the effort and accept a hot running watercooler, or use it as an excuse to throw the slant four in the scrap heap and choose a transplant.

Folks race these cars in Spec class. They are competitive and durable engines that run cool for the guys who track them hard......

so why can't we who use them on the street seem to 'get along' with them ?

divil

Something else from your original post I meant to comment on but forgot: you mentioned that you might be having issues with the climate control unit. Are you sure it was blowing hot air out of the vents when you bled it? Having the heater control valve open to the heater core is essential to get the air out. But the cc units can fail. It happened to me, no matter what I did I couldn't get hot air. Then eventually someone told me to go and look at the heater control valve and see if it was opening and closing as I adjusted the temp konb - and it wasn't! If you do have a problem with the cc unit, you might be able to work around it by pulling the vacuum line from the hcv. I *think* it will then default to fully open which is what you want.

pugface

Thanks guys

Piecing some replies together, and what I've read on other threads, there may be a common ground in the dissimilar sounding replies - perhaps they 'all do that' in that the temperature gauge moves around. As divil points out, modern cars gauges are not directly connected, but run through the computers and filtered - to prevent neurotic owners like me from worrying!

The question is how much movement is normal - I don't like getting to the third mark (944/2) - which Clark's says is 100 C

We moved across the country away from all friends and family, and one thing I didn't think about was the experts you know or have recommendations for that suddenly disappear - your lawyer, your dentist, your plumber and in this case, your mechanic. I had a superb mechanic in Chicago who would give me advice on purchase, give me tips and help for DIY, and do any work that was over my head. Trying to work up the same support group here in TX.

mrgreenjeans - To give the mechanic the benefit of the doubt, perhaps he meant some movement is normal, but maybe I didn't make clear to him the extent. The shop is a Porsche specialist, and the particular mechanic that works on the 944 not only DDs a 944, but has a 951 as a weekend car. So, logically, it seems like a good choice, but to me the car is still hot, and the interior is still hot after the A/C condenser was replace, but that's a different story...

I very much appreciate the list. I can confirm there is a new Behr cap, which was tested on my new Stant tester! I will go over the electrical stuff myself - unlike most shadetree types, I'm very comfortable with electrics and electronics, but not mechanical.

I'll confirm the thermostat and waterpump when I take the car in for A/C fix Friday, I'll keep working on bleeding the system, and then I'll start going through the rest of the list

pf

pugface

I'll try that. I am not getting heat, but I get plenty if I switch to defrost. It may be that the ambient temps (around 100) are hotter than the the thermostats max. I see you should bleed the car with the heater open, but how do you do that with the car off? I've been setting it to defrost before I turn it off, not sure if that is right.

divil

I don't think you can do it fully with the car off. The procedure I was told was like this:

1. when you fill the system, remove the bleeder screw completely, don't just crack it.

2. once it's filled, use a coolant pressure tester at the reservoir (or just blow) until you get a smooth flow of water coming out of the bleeder

3. reinstall the bleeder screw, start the car, and turn the heat up to full (and open the vents and turn on the blower so you can tell when the air is hot).

4. When the car gets fully up to temp, crack the bleeder screw until just coolant comes out with no air bubbles, then close it again.

5. This will have caused the temperature to go back down again - wait for it to come up again and repeat step 4 until you no longer get any air bubbles and you get constant searing heat from the vents all the time.

6. Other things that may help are: blipping the throttle, holding it above 2500 rpm for a while, going for a drive, elevating the front, and in extreme cases, let it sit overnight and then repeat from step *2*.

That's the sequence I was given by a mechanic friend who works on 944s a lot, as best I can remember it.