1997 528 Cooling

Mum's car. Possessed. Evil. Horrid little thing.
Started overheating a couple of years ago. Had the head gasket replaced. Runs good. No oil in the water, no water in the oil, plugs
look great. Overheating again. I bled the crap out of it. Ran great for about a week and then over heated on the interstate. Then overheated in parking lot. Then overheated under normal driving. I checked and found the push fan not working. Mum had to drive it (on the interstate) and went about her merry way. It overheated. Broke the top right radiator neck off. Upon further inspection I have found the fan clutch to appear new but is quite "loose" in it's cold operation.
This week I am replacing: Thermostat Water pump (metal impeller) Radiator Push fan Fan clutch
Am I missing something? Any other recommendations or suggestions? I already have the clutch fan and radiator out - will get the water pump, thermostat and dead fan out over the coming days. I only get so much time a day to work on it!
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Expansion tank. All hoses (since you'll have them off anyway.).
FloydR
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And...
Had not thought about the expansion tank. I did not mention the hoses because they are more routine than what I am doing. I feel much better finding a restricted radiator and think I am on the right path to get her back safely on the road.
Thanks for the feedback, folks!
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In article

Has the car always had the correct coolant changes? If so wonder how the rad got blocked?
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Why didn't you do the water pump and thermostat at the same time, just pre-emptively? Wouldn't have hurt to do an acid flush on the radiator either.

Has anyone done ANY diagnosis on this? Like checking the flow rate on the radiator? Or even pouring water into the top of the radiator and seeing how long it takes to come out the bottom?

It seems kind of silly to just shotgun everything out... but at this point you might as well now that you've damaged the radiator anyway. BUT, after doing all this... you might want to measure the flow rate. You might also want to do an acid flush beforehand anyway, just to clean whatever junk is in the block.
While you're shotgunning all this stuff out anyway you might as well replace the hoses too if you haven't done that before.
Have you been changing the fluid and flushing the system annually like the manual tells you to do? --scott
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"C'est un Nagra. C'est suisse, et tres, tres precis."

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Read my first line. Mum's car. I am intervening and yes, I probably should have before this but "she was handling it." Clutch - a bit loose. Push fan - dead. Radiator - tried running water through it. More water came out the end with the hose. Not the case with the new radiator. I believe this is the culprit. Thermostat - looks good but replacing all the same and going with the metal housing. Water pump - plastic. Going metal.
Water flows through engine well. Flushed it in case of debris from radiator neck breaking. So out of the 5 items I am "shot gunning" I have found issues with 3 and a potential problem with the 4th. I would say those are pretty good odds.
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So, it sounds like the basic issue is that lack of regular coolant changes caused the radiator to gunk up.
You could try the acid flush to clean the block out as well, since that is probably not much cleaner than the radiator. Problem is, it's apt to cause anything marginal that is sealed by corrosion to start leaking all of a sudden. Water flows through fine because the water jacket doesn't have a lot of little fiddly bits like the radiator does, so the lime can build up pretty heavily without affecting flow. It's still reducing cooling, though.
The plastic and metal water pumps both have premature failure problems, they are just different problems. Won't hurt to replace it while you have the thing apart, though. --scott
While you're at it, too... I'd change the brake fluid, power steering fluid, transmission and differential fluids too... odds are they have not been getting changed on schedule either.
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Great thanks to all. There is more of a story to this and the car has sat for several months. It has not run for an extended period of time since the head gasket was replaced but I cannot remember how long it had been since she had purchased it. Yes, used car. Within a few months of purchase she had to replace the spider web harness in the steering wheel and had everything serviced then. This fall that would have been three years ago. The head gasket was done last spring. Since then there has not been 3000 put on the car so maintenance has been a moot point. My father passed 3 weeks ago so the opportunity to get the car presented it's self. She has this and a 97 full size van so while I get the concern over paying for the parts it is easier to justify what I am doing when I sell it all on the gas mileage aspect. (van gets 15)
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Update.
The patient is terminal.
Got everything together. Bled her down. Took more time than I should have bleeding her down but I wanted to make sure it was as close as possible. 15 minutes of slow water ads, etc. Temp guage straight up the middle, rough idle but considering she had been sleeping for 7 months I figured it may be a few miles before she was happy again. Out of the driveway. Less than 1/4 mile from the house she's running like fried dog poop and the temp gauge starts coming up. Boiling by the time we get to the house and I probably could have pushed the car up the driveway faster than it was going to make it. CEL light = 3 plugs misfiring. Steam, steam, steam. I let it cool down. I fire it back up and stick the water hose into the expansion tank. Yes, we are going to eliminate any water out of the engine. Fire it up. Bad idle, the the point that the interior light is dimming in and out. <at this point it is obvious that the car is hurt, we can debate the logistics of it all but it is quite honestly cheaper to replace the entire engine than for me to buy a head and have a head and head gasket set installed so yes, I am not acting in a precautionary manner at this point> The car runs for a good 30 minutes with the hose installed. There would be seconds where the water was exiting unaided but 98 percent of the time there was air mixed in with the water. The car never got hot. It never ran worth a crap. Tonight I pulled plugs. The #2 base had the most evidence of misfiring. The #5 hole was the wettest looking (24 hours of sitting) and front to rear during the compression test: 135 120 90 105 115 140. Nothing consistent so far. I will put the radiator pressure test on it tomorrow and see what that yields, if anything.
Hopefully it's the head gasket. Won't know for sure until it's off the car. If it's the head the best price I have found on one is $750.00. Gasket kit is about 250 plus other small things, labor, etc. A complete engine is $1,500.00 (two places here in town, best engine was 111,000 compared to mom's 101,000 with a warranty on it) I can do the engine swap. What I can't do, for lack of tools is the head swap and re-timing of everything. I have looked it over in TIS and to be quite honest I am scared to try and do it in a home garage!
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Your motor, Mum's motor really, is the M52, which is very similar to the M50 used until production of the '96 model year cars -- one of the differences is the Smog Control stuff that was changed from OBD I to OBD II.
A known issue with the M50 head is that it can develop a small crack in the wall of the water jacket to the adjacent #3 Cylinder Exhaust Port. When this happens, coolant seeps into the exhaust stream and gets blown out the tail pipe. You will never know this is happening by simply looking at the exhaust coming out the back of the car, but you willo notice that the coolant level is difficult to keep up.
It is possible that an exhaust sniffer can detect the trace amount of coolant, but your eye will never see it, especially in the early stages of the crack. I found my crack because the engine happened to be parked in just the right position where the #3 exhaust valve was open, and coolant dribbled into the cylinder, then on the subsequent restart the engine locked because as the piston came up and the valve closed, the liquid could not compress and the crank stopped turning.
Sorry, I can't devise any test for you other than the sniffer in the tail pipe. Since your car is OBD II, perhaps the O2 Sensors will report an out of range condition as a result of the coolant content in the exhaust stream. My car is OBD I, and the sensor was silent on the coolant content -- I had no idea there was a problem except that I had to top off the radiator once in a while. I suppose that's an indication. But the only way to know is to pull the head and look.
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If appreciable amounts of water gets into a cylinder, the plug will show it by looking particularly clean.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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