Coolant leak from where?

I have a slight coolant leak which shows directly under the water pump. Before a daily run, I see green coolant on the floor maybe only an egg cup full. I check after the run when the engine is hot (running or not) and see or hear nothing. The lowest point of the drip is a green drop below the thermostat area. It only appears sometime during the cooling process of the engine. First question, IF the coolant reservoir was split, would the coolant from the tank appear in the driver side (LHD wheel arch)? If so, then I can concentrate on the actual pump gasket or the thermostat and pump. I hate like hell having the disturb rubber pipes of the pump and thermostat, dropping part contents of coolant into a bucket, removing the pump and fitting a new gasket or even a pump when neither was needed in the first place, only to find that the slight leak was coming from the reservoir. The problem for me is when I see the small pool on the floor in the morning, the heat of the engine has already dried up any trace of where is might be coming from. I have the air box and serpentine belt off right now. All brackets away and can see and feel around the gasket but all is dry. In fact the only thing to do is remove the hoses and 7 pump mounting bolts and the pump should be out. The spin by hand is free and quiet with no play what so ever in the pulley. If it was rough in any way I would be changing the pump right now. The car has done 71500 and I don't know if this is the original pump and thermo. Thanks for any advice in advance.

Have you considered a PRESSURE test? FWIW, this was the VERY first thing my indy did (after a quick visual of the WP, lines/hoses, reservoir). Best of luck.

Leaks can be hard to track down sometimes. FWIW - my water pump began to leak before I replaced it.

If you get the car in the air the odds are very good you'll spot the leak source. Coolant leaks leave a nice trail. I would not unbolt anything just yet. What you can do is perform a poor man's hot coolant pressure test. Top of the coolant tank with distilled water. Do not overfill but bring the level up to where it should be cold. Be sure the cap is clean and where the cap threads/seats is clean and install the cap. With the A/C off drive the car around until the engine is fully up to temperature. You want to hear/feel the radiator fans come on. Back home raise the engine RPMs to say 1500 and hold until the radiator fans come on. Then shut off the engine. As the heat load from the engine raises the coolant temperature and pressure any leak will probably show itself, sometimes with a dramatic gush of very hot coolant, so be careful. Given the location of the coolant I'm WAG'ing water pump. If this is leaking it can be visually verified but you have to have the car in the air and where you can shine a bright light. The leak will be from a telltale hole or a seal and most of the water pump housing will be hidden/covered by the pulley. But the leak will leave a stain and in fact (with my Turbo's water pump) a nice deposit of dried anti-freeze residue.

My first WAG is your water pump pulley seal is leaking. That tends to show up as a drip or coolant spot directly under the water pump, although it can travel along the motor block and show up under the lower coolant hose. At 71,500 miles it's about time for a new water pump anyway. Recommendation - since you are going to drain most of the coolant to remove the water pump, pull that lower hose on the thermostat, replace water pump, gasket, thermostat, thermostat gasket and then refill with a new mix of coolant/distilled water. Don't forget to burp the coolant system to remove air, and/or use the recommended vacuum fill method. This way you will have the lower part of the system done so even in the end if it does end up being the coolant tank, you've got the major part done. With that work done and a fresh refill of coolant your car will love you.

O k Guys I have traced the leak to the gasket somewhere behind the cog. I haven't unbolted the pump as yet. The next problem I have is removing the hoses. Is there a secret way against using screw driver under the lip of the hose and brute force to set them free from the water pump and thermostat? The sweat is tippling from me trying to pull the first one off. I have released the spring type clamp and slid it back about 2 inches. I am scared I might split the rubber and that will mean another intricate DIY job to replace with new hoses. Would it be better to loosen the 7 bolts and knock the pump free from the gasket and maybe lower it away. Then I may be able to turn the full pump in the hopes that it breaks the seal OR do the hoses have to come free before I CAN drop the pump?

If you don't have a radiator hose tool (a curved, pointy screwdriver), it can be a pain to get the hose off. Try not to tear it up too badly - otherwise, you'll be replacing it, as there isn't enough slack to cut to just cut off the torn up end. By "behind the cog" do you mean the water pump pulley? While it's possible that the gasket is leaking, it's more likely that the shaft is leaking and you're just seeing it collect and drip from the gasket. Those metal gaskets don't often just spring leaks 15 years along...

Yeh 5CHN3LL from behind the water pump pulley. I have right now a screw driver between the hose and the metal and the cap off the reservoir and the coolant is running into a bucket pretty quickly. When it stops I will try to pull the hose off again with no pressure inside the line. That may work. OK that worked for the first hose and no damage TG.

The hoses are a pain to break loose and patience is required. As mentioned, the pointy radiator hose tool is invaluable. You have to work it up under the hose in multiple places and a little sil-glyde makes it easier to keep working it. It will bust loose with a good pull once you've done this. Mechanic gloves will help keep you from busting a knuckle twisting and turning, pulling and once it gives. Good luck!

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Never had to use a screwdriver or any other tool to remove hoses. Just remove the clamp and twist the hose left then right until it breaks free of its grip on the connector pipe. Never used mechanic vinyl or rubber gloves but these might help get a better grip on the hose so it can be twisted loose.

OK got the first hose free no damage. Took 5 of the 7.. 10 mil bolts from pump BUT 2 are real hard to get too. A normal 10 mil wrench was ok until these 2. I think I need a 10 mil socket which I don't have. So I am going shopping right now.

1/4" drive 10mm socket plus a u-joint will help a lot.

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I used a knuckle (u joint) and a couple of extension bars and finally got all 7 bolts off the pump. Another question. The larger rubber hose, is that going to the thermostat?.. I need to set that free as well. I had too set free the metal small pipe to make room for the pump to drop out but now the large hose is in the way. If that hose is going to the thermostat, then I intend changing that part for a lower opening temp one. When that is free the pump should drop away. Then I can inspect the impeller and change the pump anyway as the car has done 70 thousand plus as suggested in a previous posting from one of you guys. I think it's a good idea as I don't want to be on my back again and wishing I had changed it when I had the chance. I am getting older by the second and all new parts should be good for another 100,000 miles . Only one band aid used up to this point on my hand when I was taking a small pulley off to make way for wrenches and extensions for those last two bolts. I am going to be like Krazy Ken doing all this DIY work but never intend dropping an engine as he does. haha thats not crying, that's sweating. lol

Yes, big hose to the thermostat. You're doing great!

Does anyone know what it would have cost for a garage to change out the water pump and thermostat if I had taken the car in for a mechanic to do the job for me? Approximately. It should cost me about $350 all told plus a lot of sweat and cussing.. I changed the coolant last year so I am putting back the gallon or so which I saved in a bucket. I am wrapping it up for today as I have to get the dinner ready now for my bread knife (Cockney Slang for you yanks who don't know). No rest for the wicked. Meaning me.

I would say you're saving at least $200~300 on labor and most shops charge MSRP on parts so you save there as well. BTW, please take your time to clean off the mating surfaces of the thermostat hosing and water pump (can use scott brite). The old gaskets tend to embed into the block.

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Shop quoted me $900 ... I think I paid $350 for parts and used Pentosin sf coolant at $12 a quart x 5 quarts + distilled water. Yep it took me all weekend - but I was going slowly on the hoses using screw driver in multiple spots to break seal between hose and pipe. The bottom bolts on pump are a pain. I finally got them from above - with 1/4 socket and ratchet - 90 degree u joint and using long screw driver to push the ratchet head onto the bolt and hold it there while turning - torque spec on those bolts is only 7 lb/ft if I remember right. Next question you may ask is whether to use gasket sealant or not Yep - a lot of sweat and hours for a newbie but Big satisfaction when you are done ....

Hurdi, once you realize that the pump won't just drop out like it's supposed to - and before you drive yourself insane trying to pull it down and out - I suggest you take the idler pulley off that's above the pump (if you haven't already done so) and remove the pump from the top.

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+1 for out the top. For the hoses I have used shop air and an old steel brake line with one end screwed into my air gun and the other flattened and shoved against/under the hose lip to help loosen the hoses.

Great help from you guys so far... I am struggling to drop it out so I will opt for the 'top removal'. I have the belt guide pulley off. I took that off to get that last bolt from the top. What a pain that was. I don't have an air gun for the hoses. I see the old gasket loose already. I have all the time in the world and will start later today again. I would say at this point that the gasket is not cut and is part of the thermostat as well as it left Stuttgart. No sealant is used. I am not going to use sealant. What dyawl think on that statement.

Picked up my pump and gasket yesterday at the pcar dealer...they said no sealant. Thanks for the timely trail blazing on this one. Ill probably start mine tonight

I didn't use sealant on mine. Going in from the top will also reduce the odds of you fouling up the new gasket.

No sealant required but for the love of god use a new gasket. And I don't care how fresh the old gasket looks.

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Well my water pump finally came out but my god the job was much harder and tighter than anything I have had to do on a car before. One small chip off one of the fins. No play in the bearing. I could probably get away with a new gasket but am going to replace everything now that I have it torn apart. Never want to go through this job again. I do not envy your job. The guy on You tube missed all the hard parts out from his video. Skimped and made it appear to be an easy job. No way. Didn't actually show him using a tool or loosening anything. He simply said what he was going to do. Cut the video and it was done. We can all make videos like that but he is miss leading us DIY guys to the hilt. Now if you have a pit it would be easier but not by much. Be prepared for longer job than you thought and the best of luck and watch the backs of your hands. Where gloves when ever you can. I have band aids on both now lol. Has anyone used the metal fins pump? or is that not a wise choice?

I can say I told you so. One of the best investments I made is the pair of mechanic gloves! But I'm getting older and things just don't heal as fast anymore. I vote NO on the metal impeller pump (I read a bunch on this when deciding on my new water pump). IMHO the plastic impeller pump Porsche used as OE is the right one.

I did my water pump this winter. I was able to get it out fairly easy from the bottom but it required pushing the motor bracket pretty hard to get it out of the way. And obviously removing the thermostat. I voted for the OE pump with a plastic impeller based on all of the reading here. Make sure you get the 996 water pump since the 997 isn't compatible (it is a few mm bigger). I didn't use any sealant but replaced with a new gasket which was included with the pump. No leaks and has been fine since then including a few track days. I did buy a 1/4" drive torque wrench for the job to avoid over torquing the water pump bolts. Torquing the last bolt was a bit tricky given the location but by that time I had a pretty good feel for the torque. I also borrowed an Airlift vacuum fill tool to fill up the coolant. It isn't required, but turned the annoying job of filling and burping the coolant into a fun one :-) My other tip was that I tried to remove as much coolant as possible by opening some of the hoses closer to the front of the car. But it was a royal PITA on jack stands and I'd never do it again. I'd rather just flush the coolant again in a year or two.

Re: metal impeller vs. plastic: You have to decide if you'd rather have chunks of plastic vs. metal shavings in your cooling system if you wait too long...plastic because the impeller wears once the bearing gets sloppy vs. metal shavings because the metal impeller grinds away at the engine case.

OK Guys I have on order a Porsche water pump with plastic impeller with gasket plus lower temp thermostat with gasket. Pelican were out of stock with the OEM (which would have been $257) total cost about $450. I don't intend using sealant. Kgohetz can you tell me the correct torque for the pump bolts?

I don't have the factory shop manuals to know for sure, but I found 3 references online (including one from Pelican parts) that indicated it was 10 Nm (7.5 ft-lb).

OK thanks I will buy a small torque wrench now... The parts won't be here till the end of this week I should imagine. Give me lots of time to prep the surfaces. I am using scotch brite pads. The pump part looks very clean but there is black residue on the thermostat seating where the old gasket made contact. I am afraid it would score the metal if I use anything abrasive on it. Its very smooth to the touch so maybe good enough. You guys that's successfully changed the thermostat might give me advice on how to remove the black stain without damaging a surface. Or if I even need to bother about removing the stain anyway.

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The black residual on the thermostat seating will never come off completely. As long as it's smooth and flat to the touch you're good to go.

I actually got my torque wrench from Amazon. it arrived in a few days and I didn't have to leave the house. I had considered using steel wool to clean the surface but decided that it was probably a bad idea. I think I ended up just using brake cleaner on a rag. After double checking that brake cleaner was safe on aluminium of course. It definitely helped clean it but I'm not sure it was necessary. No leaks so far. I also changed to a 160F thermostat from Paragon Products since they had one at a good price.

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well im almost done mine...got er out and ive put er back in. that "1" bolt is a supreme pita. finally got it out after heading to lordco auto to get a smaller 1/4" elbow ratchet. that was where i spent the bulk of my time. ive cracked a beer in celebration without having put that bolt back in yet thanks to all in this thread. heres some items i found that helped me out: plus, to get my hose off i used a bicycle tire lever to pry it off. popped right off. my original gasket was the metal one and it was in pretty good shape. there is a wobble in the bearing so it was time (coolant all over the floor was also a good indicator ) total time: 4 hours including beer time and trip to lordco. wouldnt have been so bad if it werent for that 1 effing bolt (and its a longer bolt to boot

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Just be careful... 10NM is nothing. Most torque wrenches can't measure that little torque accurately. You can get 10NM with just a nut driver, no wrench/ratchet handle at all. With a small 1/4" ratchet, 10NM is snug and a tiny bit more. Definitely not a torque-wrench kind of job IMHO...

I was thinking of going getting a small torque wrench but after reading your post I am unsure if it's really necessary. What do you mean by 10NM? I know when I took these bolts out, I hardly had to put pressure on them to start them off. I was thinking of guessing a hand pressure or even fingers pressure on a normal wrench. Obvioius;ly you guessed that I had got all my parts delivered. I am halfway bolting up the pump as I type. Just got the real PITA one looking down from the top on the right from engine bay. What a time consuming one that was but at least it is up tightish right now. The others I should be able to get a lot easier. 3 left on the pump. Fingers crossed. Can anyone confirm the correct lb/ft of 7 for the pump bolts? Or point me to the DIY I saw last week on replacing the pump. I am damned if I can find it now. Thanks.

http://www.pelicanparts.com/techarti...eplacement.htm mid way through the article they state 10Nm/7.0 ft.lb for the water pump and at the end state 10Nm/7.5ftlb for thermostat bolts

Well the car is finished and no leaks so far. I took it out for about an hour and took it to top temp which was steady at the left side of the 0 of the 180F mark. The outside weather temps today is 81F. I will know better as the engine cools down overnight if there is a drip on the garage floor. Fingers crossed. Thanks again to all you guys for the DIY advice along the way. BTW I didn't use anything on the bare gaskets.

Hey guys, just did my water pump back in Jan, my knuckles are still healing and my neighbors still cross the street when they see me due to the bad language. Now though I have got another coolant leak. I thought maybe it was the expansion tank or cap (seem to be the most common) as the leak is on the drivers side and forward of the block. But when I try to trace the leak it seems to be coming from a bolt on the variocam plus - driver's side top innermost bolt. I tried the hot test to see but couldnt really see if that is the source or not. There is no smoke and its only a small drip, usually dry on the floor but smells when she warms up, and the suspension is a bit wet. Im hoping its dropping from a hose somewhere higher. I dont see anything on the forums or web about a leak in this area. Any ideas?

You will get a better response to you problem if you make it a 'new thread'...

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Sounds like the coolant line on the AOS.

Hey guys, thanks I may post a new thread. Perryinva - I was thinking the same thing but the lack of vacuum from the crank and smoke in exhaust makes me think different? If its only a line and not a aos failure I suppose that could be. I'm going to have it pressure tested tomorrow. Today it leaked like crazy after a 5 mile run with the ac on and about 90 degrees ambient air temp, but tonight doing the same drive with the engine cool and no ac not a drop. Its my only car besides the wifes suv so hopefully its a quick easy fix. Keeping my fingers crossed.

Hey Perryinva, sure enough after doing a pressure test it was one of the male connectors on the aos. Getting a quote to replace (seems to be in the 1200-1800 range) Does that sound about right?