[Cloud9...68]

Sorry if this is a double post - I started writing a post, then went back through my earlier posts to check something, and my new post vanished. Strange...



Anyway, what I was saying is that I pulled the thermostat (which was very easy using a pair of 90 degree needle nose pliers), tested it in a pot of water heated on the stovetop, and found that it's working perfectly <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" /> . This is surprising, since the fat hose on the outlet side of the water pump where the t-stat is housed is barely warm to the touch, suggesting a clogged thermostat. Please check my earlier post of May 24 for a recap of the symptoms. Is it time to pull the radiator to have it flushed, as I suppose a clogged radiator could cause similar symptoms? Any other ideas?



Oh, one other question. In addition to the circlip that holds the thermostat in place, there's a large metal washer (the same diameter as the thermostat). Where exectly does this belong? Between the thermostat and the water pump housing, or right underneath the circlip?



Thanks.

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[xrad]

bad thermostat, clogged radiator and bad H2O pump can all have similar symptoms....



at least you eliminated the cheapest one...



on mine, metal washer was located between circlip and thermostat surround gasket

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[unknown4u]

Mine 968 always has run between 8 and 9.30. but never hit the 10 o'clock but nower days something has changed.

Its always stays around the 8 o'clock mark what ever I do.



The first fan kicks in. I think it is now properly working after all. <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />



I think one of the relays did not work properly that kicks in the first step of the fans.

I'd always that that it worked properly. I didn't know because it has always bin that way.



Maybe you have the same problem?

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[Cloud9...68]

I don't think my issue is related to the fans, which come on just beyond the 8 oclock position, and really blow up a storm.



I just got back from having the radiator checked, and the guy at the shop says it is flowing perfectly, with no restrictions whatsoever.



I also think (hope, pray) it isn't the water pump, because the car started running warm late last summer, before I replaced the pump, and it ran about the same after I replaced the pump and thermostat in April of this year. It's just very recently started running extremely hot.



The guy at the radiator shop says it sounds like I have an air pocket in the system. I think he may be right, because, for whatever reason, I've always had a very hard time getting all the air out of this system. I replaced the coolant in March of '07, and despite multiple attempts to bleed the system using a pressure bleeder, it ran very hot, especially (of course) with the onset of the summer. It took many more attempts with the pressure bleeder to get most of the air out, but I don't think I ever got it all out, because it has never run as cool after this flush as it did before.



I'll do another search, but how common of a problem is this? I've never had a car with a cooling system that's this hard to bleed, so I wonder if I'm doing something wrong. Does anybody have any good tips on how to ensure that I've gotten ALL the air out of it, including any pockets that may be buried far from the bleed screw? It seems that getting any "deep pockets" like this out would require running a ton of antifreeze through the bleed screw, which would make a huge mess, and be very wasteful. Thanks.



Oh, and thanks, xrad, for the info as to the location of the thermostat washer.

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[Cloud9...68]

Ugh... Things are NOT looking good. I put everything back together (mainly the new thermostat), bled the system using both the gravity and the hand pump pressurizer methods, started it up with the heater full on, and the temp gauge quickly got to the 9 oclock position just idling in my garage. I can wrap my hand around the lower radiator hose, and it's literally cool to the touch - not even lukewarm. Which is also a good description for the temperature of the air blowing out of the vents. I'm afraid I've ruled everything out but the water pump. It's a rebuilt unit from Paragon I installed a few weeks ago as part of my belt job. Yes, I went with a rebuilt unit against the advice of many people on this board, but my big fear was leaks, and there's no problem on that front - the system is tight as a drum.



So if it's the pump, it must be that the impellers are either broken (?), or the shaft is not turning (wouldn't that make a huge racket?). I've never had a water pump fail on any car - for those who have had this delightful experience, what are the symptoms?



The one faint glimmer of hope I have that it may not be the pump is that the car has been running warm since last summer, long before I installed the rebuilt pump. To be honest, it's never been right since I flushed and replaced the coolant in March of 2007 (which is significantly dampening my enthusiasm for ever doing that again...). Before that, the gauge never got above 8 oclock. Ever since, it's been between 8 oclock and 10 oclock, which sounds like, despite more attempts to bleed the system than I can count, the system is still full of air pockets. But I don't know what more I can do to get the thing bled.



Any other suggestions, as I face the prospect of tearing off the front of my engine again to replace the pump? Thanks.

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[SpeedRacer64]

Have you checked for the presences of CO2?

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[Cloud9...68]

I just thought of something. If there's an air pocket or pockets buried deep in the bowels of the engine's cooling passages, which is creating a blockage and preventing flow of coolant to the radiator, I don't see how pressurizing the reservoir and opening the bleed screw will ever get it out.



So, why not really bleed the cooling system the way we bleed our brakes - by screwing a fitting into the hole where the bleed screw goes, with a tube on the other end of the fitting, pressurizing the reservoir, and pushing ALL of the coolant through the system? It wouldn't even consume any of the pricey coolant, because I could collect it in a clean bucket (this coolant is nothing if not clean at this point!). Has anybody ever tried this? Can anyone think of any downside, other than the fact that I'll have to repeatedly remove the fitting for the pressurizer to keep the reservoir full? Thanks.



[quote name='SpeedRacer64' post='53748' date='Jun 1 2008, 09:32 AM']Have you checked for the presences of CO2?[/quote]

I just saw your response between my new posts. What do you mean, exactly? CO2 in the coolant? If so, how would I check for this, and how would I know if it's CO2, vs. air? And where would the CO2 be coning from? Is this something you've run into in the past? Thanks.

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[xrad]

if the h2o pump is working and the radiator is patent, air should rise to the two highest points in the system, the bleed screw and the overflow/reservoir tank. system is designed this way. You should be able to crack the bleed screw until the side hole shows, then fill reservoir slowly until it is at appropriate level. close screw and Run engine until up to temp. Once thermostat opens, reservoir should drain into system the appropriate amount needed. Let cool and just add the needed amount of antifreeze to reservoir.



it is rare that there is an air trap/pocket if system was bled correctly (unless h20 pump not working ). Do you have hot heat inside the cabin?...that would make me think the pump is OK.



ALSO, check hoses from reservoir to rad and system. perhaps a clog in the small upper rad hose going to reservoir. alot of muck ends up in the reservoir and the small hoses.



How did your mechainc check rad flow?



Thermostat facing right way?



hate to say it but you might need to get a NEW pump.

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[SpeedRacer64]

CO2 would be entering the coolant system if the head gasket has failed or worst yet...if the motor over heated to the point it has cracked the cylinder head. Radiator shops typically have this tool...it’s tested at the radiator cap. I don't think this is your issue...but you should check to rule it out.

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[unknown4u]

Is the main toothed belt at the correct tension?

Why I ask this? Because this one is driving the pump. When the tension is not correct or it slips because the hydraulic tensioner is bad you can have the same symptoms because it is not running............

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[Cloud9...68]

[quote name='xrad' post='53750' date='Jun 1 2008, 10:01 AM']if the h2o pump is working and the radiator is patent, air should rise to the two highest points in the system, the bleed screw and the overflow/reservoir tank. system is designed this way. You should be able to crack the bleed screw until the side hole shows, then fill reservoir slowly until it is at appropriate level. close screw and Run engine until up to temp. Once thermostat opens, reservoir should drain into system the appropriate amount needed. Let cool and just add the needed amount of antifreeze to reservoir.



it is rare that there is an air trap/pocket if system was bled correctly (unless h20 pump not working ). Do you have hot heat inside the cabin?...that would make me think the pump is OK.



ALSO, check hoses from reservoir to rad and system. perhaps a clog in the small upper rad hose going to reservoir. alot of muck ends up in the reservoir and the small hoses.



How did your mechainc check rad flow?



Thermostat facing right way?



hate to say it but you might need to get a NEW pump.[/quote]



No, I definitely don't have heat coming into the cabin. The air blowing out of the vents with the heater set full on, and the temp gauge at 9 oclock, is barely lukewarm. When I installed the rebuilt pump in March, the air blowing out of the vents with the heater on was very warm, so if the pump is bad, it's gone bad recently.



I'll take a look at the small hoses, but things seem to be draining from the reservoir into the engine OK, so I don't think that's it, but it's worth a look.



As to the direction of the thermostat, I have it facing such that the spring is not visible; most of the unit (including the spring) is facing the water pump. This allows the smaller, round surface that the spring pushes against to seat against the rubber gasket in the pump. This seemed like the only logical way for it to go; I couldn't find a diagram in the manaul. Do I have it correct?



I didn't see the radiator guy check the flow, so I don't know how he did it, but he was very sure it was flowing correctly; no doubt in his mind whatsoever. He looks like he's been doing this for a few decades, so I didn't feel any need to question him.



Sigh... Yes, it is looking like I need a new water pump. I keep clinging to the fact that it was running warm even before I put in the rebuilt one, which says the problem is unrelated to the pump, plus I'm scratching my head as to the mechanism by which a newly rebuilt pump would simply fail to pump water, without leaking, or making any noise. And I want to be ABSOLUTELY sure the pump is bad before tearing the front of my engine apart again. Like I said, the temp has never been the same since I flushed the system in March of 07. Thanks for all the suggestions.

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[Cloud9...68]

[quote name='unknown4u' post='53754' date='Jun 1 2008, 12:28 PM']Is the main toothed belt at the correct tension?

Why I ask this? Because this one is driving the pump. When the tension is not correct or it slips because the hydraulic tensioner is bad you can have the same symptoms because it is not running............[/quote]

I installed a new tensioner when I replaced the belts a few weeks ago, so I assume the tension of the timing belt is correct.



I will go ahead and take off the belt covers and see if I can tell if the impeller can spin, or if it's frozen. When I installed the pump, I remember thinking that the impeller shaft was pretty tight against its bushing - it took a bit of effort to get it to spin, but I took that as a good sign that the seal was tight, and consequently wouldn't leak.



[quote name='SpeedRacer64' post='53751' date='Jun 1 2008, 10:03 AM']CO2 would be entering the coolant system if the head gasket has failed or worst yet...if the motor over heated to the point it has cracked the cylinder head. Radiator shops typically have this tool...it’s tested at the radiator cap. I don't think this is your issue...but you should check to rule it out.[/quote]



OK, I understand now. At the moment, the car isn't driveable, so I would have to have it towed to check for CO2 in the coolant. I don't think it heated to the point that it caused any damage, because it never got above the 10 oclock line. Also, the funtamental problem is that the thermostat isn't opening, which is why the lower radiator hose is not getting warm, and I don't see how CO2 in the system could cause this, unless it generated a cluster of bubbles that restricted the coolant flow. But I just bled it again, and didn't get a single bubble. And if CO2 were leaking into the cooling system from a failed head gasket, I would think the coolant level would change, either increase due to the intake of CO2, or decrease as a result of leaking into the cylinders. But the level is staying rock solid stable.

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[Cloud9...68]

The saga continues... I took the top belt cover off, and, expecting that I should be able to turn the water pump a little, despite the friction exerted against it by the back of the timing belt, I found that actually, I couldn't turn it in the slightest. Convinced this was a sign that the water pump had seized, I bit the bullet and removed the belts. But, as soon as I got the timing belt loose, I found that the water pump turns very easily, and smoothly. It's still possible there's a broken impeller, but I doubt it. Also, I'm very reluctant to remove the water pump until I've ruled EVERYTHING else out, because one of the pump bolt's threads is in pretty bad shape - it's holding fine, and not leaking, but I know that if I remove it, I will have to re-tap the thread, which is about the last thing I want to do.



So, I'm back to thinking there's some sort of obstruction somewhere in the cooling passages (not the radiator, since I've already had it flow tested). I think this because the car started running warm long before I installed the new (rebuilt) water pump and the new thermostat.



As I was working on the car tonight, a neighbor walked by and asked if I had thought of trying to reverse flush the system. Hmmm... Sounds like a pretty good idea. Have any of you guys ever done this? I did a search, and every link I could find recommends doing this at a shop, where they have the equipment to blow compressed air through the system. But I know there are home kits made for this, where you hook up a hose to a tee that you install in the heater line, I think. Any thoughts? I'd have to tow it to a shop if I decided to go this route, but is this works, it sure would beat re-tapping a $bazillion engine block. Is there any downside to doing this? Thanks.

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[Cloud9...68]

Ok, now I'm starting to get worried (I wish I could change the title of this thread to something that conveys the more heightened sense of concern I'm feeling as I dig deeper and deeper into my problem...)



Anyway, I took the water pump out... and it's perfect. The impeller is not loose from the shaft, there's no wobble at all, and it spins smoothly, with what appears to be just the right amount of resistance. It has a black plastic impeller.



So, I've now ruled out the thermostat and water pump, and the system isn't losing a drop of coolant, over a period of many weeks from the time I put everything back together (in March), and when I first noticed it starting to run really hot (in late May), so it doesn't seem like it could be a blown head gasket. My recent oil analysys showed no antifreeze in the oil. The hoses are about five years old, and there's no sign that any of them are plugged, judging by how well they drain (and trust me, I've drained this thing MANY times now).



The fundamental problem is that the system isn't flowing any coolant, as evidenced by the fact that the fat hose on the output side of the thermostat isn't getting warm, nor is there warm air blowing into the cabin when I run the heater. And of course the temperature gauge indicates very hot - the last time I drove it, it got to the 10 oclock line, where historically, it never used to get above 8 oclock. The heater did work in March when I finished the belt job. The car started running warmer than before late last Summer, so this isn't a new thing, it's just become too hot to drive in the last couple of weeks.



So is there anything else it could be besides a massive blockage? But given the size of the coolant passages, where could a piece of crud (or whatever) large enough to completely stop my coolant flow come from? Has anybody ever experienced or heard of anything like this? What should I do next? Tow it to a shop that can power back-flush it? If the blockage is as big as it would have to be to cause this, would back-flushing be enough? Am I looking at dismantling the engine and getting in there with brushes and such to clean out the passages? Yikes! Tell me it can't be!

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[968rz]

Cold rad return hose and no warm air from the cabin heater are classic signs of air in the system, re-bleed the system with the heater on (fan off). I don't think a plugged passage would cause both things at once (but I could be wrong).

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[Cloud9...68]

I have bled and bled and bled this system, using every method in the book, but I haven't tried it you with the heater on. Why do you think having the heater on would make a difference? Do you think maybe I've had an air bubble (it would have to be a whopper) in the heater core, that has made its way into the main system, and this is now causing the blockage? It sure would be great if it were as simple as this (after having dismantled half my engine to get to the darn water pump, which now means I'll have to heli-coil at least one of the pump's threads before putting it back together. AAARRRGGHHGHH!!!!!) Sorry, getting a little frustrated.



Thanks for the suggestion - sometimes the most elusive problems end up having very simple solutions. I can only hope this is the case with mine...

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[flash]

arrrrgh - step one - TURN THE HEATER ON - that is a must in bleeding the system - temp to full hot



then, when the engine is running, this is a chance to look at the hoses - make sure one is not collapsing



while you have the pump out though, and the radiator is empty - FLUSH IT OUT - this will also give you a good indicator of any blockage there



remember to use phosphate free coolant and distilled or de-ionized water and NOT tap water when refilling



make sure the line to the overflow tank is clear too

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[Cloud9...68]

Thanks for the quick responses, guys.



Well, I did turn the heater on the last time I drove it, when it got real hot, and then I pressure-bled it with the heater still open, so in effect, I did bleed it with the heater on. Also, when I first put it back together after the March belt job, I took it for a long drive with the heater full on (got nice and toasty inside the cabin), and then power-bled it again. But that was when the o-ring for the hose fitting on the front of the pump was leaking, so I wasn't able to pressurize the system very much, so maybe I wasn't able to get all the bubbles out of it. So, bottom line, I have *sort of* beld the system with the heater on, but maybe not as rigorouosly as I could have. OK, I'll put it all back together, open the heater, pressure bleed it, drive it (if it doesn't overheat while idling in my garage), pressured bleed it again, and hopefully tis will take care of it. Gonna be awhile, though, since I've never used a heli-coil before, and I've pretty nervous about my maiden voyage being on a priceless aluminum block...



Flash, to answert your other questions: I'll take a close look at the hoses with the engine running, but I've had them off a number of times now, and they're still quite supple, so I think they're OK.



I've already flushed the radiator at a shop - they said it flowed perfectly.



I've used phosphate free coolant since I first flushed it, but the stuff that came out was green, so the previous owner clearly didn't. This may be part of my problem, I suppose, but I kind of doubt it.



Back to the bleeding real quick, could one of you guys please explain why it's so important to bleed with the heater open? If the heater was closed when I replaced the water pump and thermostat during the belt job, how could air have seeped into the heater core and its associated tubing? I ask because Clarks Garage doesn't mention opening the heater in their description of bleeding the system. I guess I'm just baffled how air bubbles could cause such a massive shutdown of flow of coolant, given that the pump should move them to the highest point in the system, and my recent attempts at bleeding hasn't produced any air bubbles. Sorry, I don't mean to sound argumentative, especially since you guys are being nice enough to take time to offer suggestions, I just want to understand. Thanks.

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[flash]

because the heater core is the highest point in the system - therefore, the air will go there

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[PorscheDude]

This is something that has worked for me in the past.

If you have access to compressed air,

With the engine cold Insert the air nozzle in the water fill neck

and try and seal the nozzle as good as you can using a shop rag.

Use the compressed air to force the air pockets thru the system.



Then use the usual bleeding procedure.

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