Garth S

Jeff,
There should be no magic here .... I've drained coolant from and refilled your car twice: never an air lock issue. Perhaps, just bleed again in the same fashion. I would expect the system to be air free very quickly .... hopefully

Jeff928S4

This "other issue" is scaring the hell out of me!!

I assume they literally just poured coolant into the overflow tank until it stopped....and they did a full flush too. This would leave a lot of air in there I suspect.

Bill Ball

If they just dumped the coolant in until the bottle filled up and sent you on you way, then they are not too sharp. I mean, this is a general care care issue, not 928-specific. If this is the case, then you need to worry how they flushed the cooling system and established the correct mixture, especially in your neck of the woods. If they did not remove the block plugs, then 2 gallons of flush remained in the block, which would not have had any antifreeze at all. If they used 50/50 premixed coolant, then you are low on antifreeze. A good shop would know about the plugs and pull them. I don't pull the plugs, but I flush the block thoroughly with our very soft tap water, leaving 2 gallons of clean water in the block, and add about 2 gallons of 100% coolant to achieve a 50/50 mix. But this relies on having soft tap water. Others run several gallons of distilled water through the block after a hose flush. You can check the mixture with a cooling system hydrometer. Hopefully they did, and all is good, but the questions need to be raised.

Jeff928S4

A bit of an update....

I went out and ran the car up to operating temp in the driveway and it was pumping out heat, still subjective to engine revs......if I revved it, the heat was more hot. After a while...the heat seemed to be pretty hot, even at idle.....but it would still get more hot with revs. It ran a tad more hot than normal, again, according to the temp gauge.

I waited for the fans to come on and checked the lower hose. It was actually kinda cool and not really "hard".....heck, the upper hose was easy to touch and even the engine was touchable with a bare hand on the heads, manifold, etc. The temp guage was showing the needle on the last white line, but the engine was not HOT. I've touched it before and it has been wayyyyy more hot in the past. Even the fans thought it was "hot".....mind you, it was -7 last night, but still. I mean, you'd think with the fans coming on, it would be a bad idea to place a bare hand on the manifold due to it being hot.

So.....now the bad news. After all this playing around, I shut it down and as I walked by......coolant POURING out of the bottom. I get out the flashlight and start looking around. I can see it dripping from the bellypan on the drivers side...kinda below the far right (if looking at engine from front) pully......but when I look in the engine bay, there doesn't appear to be any coolant coming from above his area (where I recently had the water manifold leak).

So.....coolant is leaking when the car is fully warmed up (doesn't appear to be leaking when cold). It's not coming from any of the hoses that run in and out of the water manifold, nor anywhere around the area where the manifold sits on the block. It appears dry around the reservoir tank area. I can see coolant on the bellypan......there doesn't appear to be any on the oil pan above where it drips out of the bellypan. When the car is warm and leaking, there is a small amout of smoke coming from the general belt area from what I assume is the coolant hitting the engine.

Sadly, I'm guessing my waterpump is leaking.

It is currently at the shop who did the water manifold. They will pop it up on the hoist and drop the bellypan and check it out. I'm expecting a call that says, "Not sure where it's coming from, but it looks like it's dripping from under the belt cover on the left".

Could this explain the fluctuating heat? Any chance it's still an air issue and maybe the coolant I'm seeing is somehow blowing out somewhere? Just wishful questions, is all.

I'll report back with the diagnosis from the shop........

Garth S

Keep us tuned in - can't recall if you had replaced the pump, but if so, was it a plastic impeller?
There's working room for a 4th car in my garage, so you always have options .....

Jeff928S4

First off, I want to sing the praises of a one Mr. Garth S.

If this man did not exist, my life as a Porsche 928 owner would be about 93.74% less gratifying as it is now.

Knowing Garth is nearby is like being a Catholic priest who lives next door to the Pope.


As for the pump, it was not replaced when the timing belts were done....it was checked for leaks, etc. I believe this pump should have around 60,000 miles on it. I thought it might make it to the next belt change, perhaps I was way off base.

Looks like I may get some timing belt removal experience!!

SteveG

60,000!! You gambled and lost, sorry about that. Some would say that was no gamble. Not laughing, but most humor is based on other people's pain.

Be glad it went slowly and didn't do something violent.

Jeff928S4

This is true.

I had a belt snap in my 944 and it bent 8 valves. Ya'd think I'd learn.

Garth S

Tough to make any call without seeing the evidence; however, following the symptoms reported from the beginning of this thread, it would be feasible to surmise that insufficient coolant was in the system after the reinstall of the coolant bridge. Following brief operation, that would be sufficient for the heads, top hoses, various plastic bits, etc to have seen steam vs coolant .... which can contribute to any one of a number of failures: hopefully, that number is zero.
Also, new thermostats do not always open as they should - caught on that once, so now, every new one is treated to a hot bath before install.
It may be something as simple as a pump failure. Coincidence it may be ... but I'll stew in suspicion for a bit longer ...

WH928

if you belive there is air in the system, what i do is charge the coolant bottle with compressed air via small return hose, plug disconnected hose, remove small hose on top of radiator if you car has one charge tank with air and wait for coolant then put hose back on and remmove plug on the hose dissconected from bottle. charge bottle and wait for coolant you have now dissplaced all air with coolant . also make sure heat valve is open

Jeff928S4

Went and picked up the car last night and was told that the leaking coolant was due to the lower rad hose clamp being loose. When he pressure-tested it, he could hear a "hissss" from where it was leaking.

Car was running in the shop.....with full heat working, regardless of engine RPMs. The mechanic said the system showed 15 PSI when tested.

"Great" I thought......just a hose. It was running at full operating temp and no coolant appreared to be leaking.

I drive home......I drive to work this morning (it's still holding coolant in expansion tank) and when I get out and take a gander....drip, drip, drip from the bottom.

What I figure is that the floor in the shop is completely flat, so perhaps it WAS still leaking when it was running in the shop, but it was collecting in the bellypan. As soon as I parked on a non-flat surface, it dripped.

It's going back at lunch, where I will ask them to run it without the bellypans and watch for leaks.

What is odd is that before the leaking hose was found, it appeared to be dripping from the front, drivers side of the engine - now it is dripping from a location that is further back.....like right below the engine.

Oh well, it looked good there for a bit. Will have to wait till this afternoon to see what is leaking now. The saga continues........

Jeff928S4

Got the update....

Appears to be leaking from behind the crank......i.e. waterpump.

Now, should I order a new belt too? Will the old belt be contaminated by the leaking coolant?

Bill Ball

I hope these guys are decent mechanics. The loose hose clamp indicates thery aren't real thorough. Also, pressure testing is just one factor. You have some evidence of lack of flow (i.e., bad water pump) - the cold lower hose, relatively poor heat when idling, hot temp gauge reading. Anyway, it looks like you are headed for a water pump replacement.

The coolant will not hurt the belt, but as you are going to have the pump out, consider a through look at the TB system. Might as well do the job unless it was very recent.

Do you really trust the guys that are working on your car? Not to burden Garth, but I'd trust him to do my water pump and timing belt more than I would trust me, and I trust me. This is a rather specialized job. Certainly even a backyard mechanic like me can learn how to do it properly, but I wouldn't want these guys learning at my expense.

Jeff928S4

I only took my car to these guys because they have *some* experience with 928's, and like you mentioned, I didn't want to burden Garth. I figured they could pull off a water manifold re-seal.....although, I believe they charged me like 4.4 hours to do it.

I would not trust anyone other than Garth to do anything Timing Belt related or anything "major". Garth is da man!

Garth S

Jeff,
Knowing me as well as I do, I'd recommend Bill .... but as his territory appears to cover all the west coast, I'll be glad to help.
There's still a little too much coincidence involved in this event sequence to fit with a simple pump failure, but anything is possible: I do want to test that new thermostat against the old one. Dig out the work order/parts list from the prior TB replacement job and give me a call - we'll get this one back on the road.
BTW, also inspect the TB through the air tube holes and guesstimate the rate of coolant loss. We have to determine if it's safe for you to drive a 100Km.