After changing timing belt there is a coolant leak

I have changed the timing belt on my car 3 times now. Never had problem.

The local shop quoted my Dad "$500-$800" to change the timing belt, so naturally I offered to do it...for a little less
So last weekend I changed the timing belt, water pump, hoses and belts. I put it all back together at dusk. It fires up nicely. But, there is coolant leaking from the bottom at a rate that falls someplace between dripping and a full fledged stream. I couldn't see very well, but I checked all the hoses and found nothing. It was coming off the block, right in the front, with a source someplace underneath the timing belt covers.

Fine, I say. I must have mangled the water pump gasket when I put it on. The hoses were new, and it wasn't too hard to verify that they were all tight and not leaking. I overnight a new water pump gasket, and on tuesday take it all back apart. I remove the water pump to find a gasket that perhaps could have been fitted better. I also found a tiny bit of old gasket along the edge under the tensioner that I had missed. I gave special attention to making sure the outside was 100% smooth, and that the gasket went on perfectly. No gasket was sticking out, I'm positive that 2 of the bolts were through the gasket holes, and the 3rd bolt I gently pushed in so as to be sure it was nailing the gasket dead center. Everything tightened up well, the edge of the water pump showed no signs of problems.

I put it all back together last night, fired it up again, and AGAIN the same coolant leak. This time I was armed with a flashlight and a little bit of day light left. I got under the car and could tell that the coolant was coming from around the water pump. What I can't be sure of is if it's coming from under the water pump, or if it's coming from above the water pump and running down the edge of it. Because of the timing belt and covers, fan, etc, I can't see the top of the pump.

So, what are the chances that I managed to botch two water pump seals? Is this actually a hard thing to do, and I got lucky the first 3 times I did this on an E30? Any tips or tricks? My mechanical ego is at an all time low

When I take it apart a 3rd time, with a 3rd seal in hand, I'll be looking at everything very very carefully. I'm positive it isn't the hoses. Perhaps the water pump is bad/cracked? Perhaps the head gasket is shot? Would it be bad to add some other form of liquid seal to assist the tiny standard gasket in sealing the water pump?

If I take this apart a third time, find nothing, and put it back together only to find it still leaking, I'm going to shoot myself

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

How about using some chalk (or similar) to find the source of the leak first? Make sure the engine is dry before you start putting it on, then run the engine just for a little while to get it leaking and check for the leak.

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Michiel 318iS
How about using some chalk (or similar) to find the source of the leak first? Make sure the engine is dry before you start putting it on, then run the engine just for a little while to get it leaking and check for the leak.

More detail? I'm unaware of this method of trouble shooting.
Is the idea to coat all surfaces and then see where the chalk is missing from? I would think chalk might be bad for belts?

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil
Would it be bad to add some other form of liquid seal to assist the tiny standard gasket in sealing the water pump?

I've had the exact same thing happen. Adding gasket sealer to the water pump gasket fixed it. Supposedly with clean, smooth faces you're supposed to be able to install the water pump gasket dry. But IME using gasket sealer is the way to go, and ensures that you won't need to keep doing it over and over, and risk shooting someone.

Just make sure you get the kind of sealer that is easy to remove the next time you do the job. I never remember what kind, so I just ask at the parts counter.

__________
Dave
'91 325iX

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Dave_G

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Earendil
Would it be bad to add some other form of liquid seal to assist the tiny standard gasket in sealing the water pump?

I've had the exact same thing happen. Adding gasket sealer to the water pump gasket fixed it. Supposedly with clean, smooth faces you're supposed to be able to install the water pump gasket dry. But IME using gasket sealer is the way to go, and ensures that you won't need to keep doing it over and over, and risk shooting someone.

Just make sure you get the kind of sealer that is easy to remove the next time you do the job. I never remember what kind, so I just ask at the parts counter.

A few of the pump mounting bolts go through in to the cooling system, these lower bolts should be "bedded". I always clean the threads in the block with a tap and solvent, blow them out to dry then put some gasket silicone sealer on the bolts before they go in.

Most people fail to do this and always have a weeping cooling system, that always needs to be topped up.

Rick

I hope the above suggestions pan out but new water pumps have been known to have "issues". What about taking it all down and then pressure testing it to see exactly where the coolant is coming from?

alan



Edited 1 time(s). Last edit at 02/18/2011 04:01PM by alanrw.

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alanrw
I hope the above suggestions pan out but new water pumps have been known to have "issues". What about taking it all down and then pressure testing it to see exactly where the coolant is coming from?

alan

Good idea, but unfortunately outside of my current tool set. Now that I know that it's possible for the waterpump to leak with a good gasket, I'm inclined to give it some silicone sealer and see what happens. As a last dumbfounded attempt I'll find a way to pressurize the system. However, since the radiator and all hoses need to be attached, my view would still be moderately obstructed. However not as much as having the fan belts, and timing belt there

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil

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alanrw
I hope the above suggestions pan out but new water pumps have been known to have "issues". What about taking it all down and then pressure testing it to see exactly where the coolant is coming from?

alan

Good idea, but unfortunately outside of my current tool set. Now that I know that it's possible for the waterpump to leak with a good gasket, I'm inclined to give it some silicone sealer and see what happens. As a last dumbfounded attempt I'll find a way to pressurize the system. However, since the radiator and all hoses need to be attached, my view would still be moderately obstructed. However not as much as having the fan belts, and timing belt there

A warning about radiator sealer, it's a mistake in an E30.

I am with Dave on the gasket sealer. That wimpy thin gasket would be a challenge to seal much of any thing. coat both sides of the gasket with Permatex non-hardening gasket sealant. Also use some anti-seize sealant on the bolts too. The Permatex is not the right thing for the bolts as it makes them very difficult to remove.

Bob in Lake Havasu

You clean and dry the location where you think it is leaking, spray/blow/brush over the chalk and after a short run, you'll see where the chalk is wet. Don't wait to long as the water can creep in the chalk. Afterwards you just wash it off.

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Bob in Everett
I am with Dave on the gasket sealer. That wimpy thin gasket would be a challenge to seal much of any thing. coat both sides of the gasket with Permatex non-hardening gasket sealant. Also use some anti-seize sealant on the bolts too. The Permatex is not the right thing for the bolts as it makes them very difficult to remove.

Bob, There are many cars with threads going in to the water jacket; alot of headbolts are set up that way and you have to bed them with silicone sealer or they will not seal. When it comes to removing the head (or water pumps whatever) the bolts come right out. You can also wrap the threads old school with sealing thread.

I neversieze everything but when you're going in to the water cavity with a bolt or stud you must seal it... That's just procedure guys. Anything else is a crapshoot and double or triple work.

Rick out

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rkj
A warning about radiator sealer, it's a mistake in an E30.

I've never assumed such additives worked, or worked well. I'm also sure that, even if it weren't bad for the chemistry of our engines, it wouldn't plug the leak I have ;-)

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rkj
Bob, There are many cars with threads going in to the water jacket; alot of headbolts are set up that way and you have to bed them with silicone sealer or they will not seal. When it comes to removing the head (or water pumps whatever) the bolts come right out. You can also wrap the threads old school with sealing thread.

Do you mean that as cars in general? I'm pretty sure when I took my M20 apart that the head bolts did not sink down into the coolant area. I certainly didn't find documentation of using some sort of sealant on the head bolts.

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I neversieze everything but when you're going in to the water cavity with a bolt or stud you must seal it... That's just procedure guys. Anything else is a crapshoot and double or triple work.
Rick out

The trick is knowing that you are going into a water cavity to begin with!
Like I said, I've done this three times on my own M20 engine without a problem. And on my Dad's M20 the lower bolt hole did not leak coolant even with the bolt removed(the coolant level was still above it). I would not have guessed that some of the water pump bolts sunk into the coolant system, and nothing in the Bentley, the Pelican Parts article, or my own experience would have me think differently. To be clear, I completely believe you guys that this happens. But surely it must be a rare thing? I can't think of any other "gotcha" quite this big that both the Bentley AND a well written Pelican article missed. As always, you guys never miss anything

I'll swing by NAPA this week and see what they have in the silicone and sealant department. I have yet another seal coming tomorrow just to be sure. I'll tackle it this weekend...if it doesn't snow.

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

I don't remember any of the water pump bolts on my M20 going through into the water jacket either. Maybe that's an issue on the 4-cylinder engines.

Is it a brand new water pump, or did you put the original pump back on?

I might be imagining this too, but I seem to remember the water pump has a small drainage hole at the bottom where it mates against the engine block. If the water pump shaft is worn and no longer sealed properly, the coolant will weep out of this drainage hole and run down the face of the engine block.

If it is a new water pump, it's still possible you got a dud. I had a brand new water pump installed once with a new timing belt and it made horrible shrieking noises from it's bearings. The guys who installed it tried to tell me that the noise was coming from the fan clutch, so they swapped that too. The pump still shrieked and two days later, before I had chance to bring the car back in, the pump gave out altogether and puked all the coolant.

After that, I've always done my own timing belt and water pump replacements.

Brand new water pump. I'll be inspecting the water pump very carefully for defects this time around. Any idea what the drainage hole is supposed to be draining? Assuming it exists

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil
Brand new water pump. I'll be inspecting the water pump very carefully for defects this time around. Any idea what the drainage hole is supposed to be draining? Assuming it exists

It could well be a figment of my imagination. I dunno for sure. Maybe there is no drain hole.

The point though, maybe your gasket seal is fine but the pump itself is leaking through the shaft seal.

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Ferdinand
The point though, maybe your gasket seal is fine but the pump itself is leaking through the shaft seal.

It's possible, but having experienced this myself, my bet is on the gasket seal. That's where mine leaked, and like Tyler's, it wasn't so much a leak as a gushing torrent. And yes, The surfaces were clean, dry and smooth before I put it together! The second time around, gasket sealant made everything right again.

__________
Dave
'91 325iX



Edited 1 time(s). Last edit at 02/22/2011 10:32AM by Dave_G.

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Dave_G

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Ferdinand
The point though, maybe your gasket seal is fine but the pump itself is leaking through the shaft seal.

It's possible, but having experienced this myself, my bet is on the gasket seal. That's where mine leaked, and like Tyler's, it wasn't so much a leak as a gushing torrent. And yes, The surfaces were clean, dry and smooth before I put it together! The second time around, gasket sealant made everything right again.

I assure you guys, after doing many waterpumps on 2.5 and 2.7 liter motors, the bottom one or two bolts that hold the pump on go in to the water cavity. Out of all those done here not one has leaked. I use copper rtv silicone in the permatex tube (I'll check the brand when I go in to the shop today.

Next time you're doing a pump run a piece of welding rod through the bolt holes on the lower pump bolts, you'll see what I'm talking about. The trick is getting them (both the bores and the threads on the bolts) clean so the silicone seals tight.

Rick

The water pump will have a shaft seal under the pump impeller that keeps coolant from coming out. Usually these seals are a "face" seal that has flat surfaces requiring a tiny amount of liquid to be between the flat surfaces to lubricate them. The layer of coolant is so thin that very little actually leaks (about 30 millionths of an inch). The drain hole lets any excess leakage out so it will not get into the grease that is packed into the pair of bearings pressed into the body of the pump. Coolant will dissolve bearing grease and soon the bearings will fail.

Bob in Lake Havasu

After some silicone gasket sealer black on either side of the paper seal that comes with the pump, and some thread sealer on all the bolts, I now have a leak free engine! Woot!

Thanks guys. My self confidence in car mechanics has been restored, for better or worse

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil
After some silicone gasket sealer black on either side of the paper seal that comes with the pump, and some thread sealer on all the bolts, I now have a leak free engine! Woot!

Thanks guys. My self confidence in car mechanics has been restored, for better or worse

There ya go. Did you see if those lower bolts ran in to the water cavity?

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rkj

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Earendil
After some silicone gasket sealer black on either side of the paper seal that comes with the pump, and some thread sealer on all the bolts, I now have a leak free engine! Woot!

Thanks guys. My self confidence in car mechanics has been restored, for better or worse

There ya go. Did you see if those lower bolts ran in to the water cavity?

I know that the lower left bolt does not. One can actually look inside and see (and feel) that there is a molded spot for the bolt on this car. If that molded spot was not there, the bolt would indeed sink into the coolant cavity and the bolt threads would be exposed. The middle right, I can't tell, and the top one I don't think would hit the coolant cavity.Also, if the top and middle bolts DO sink into the coolant cavity it would be very very small. I know that when I pulled the bolts that nothing came out of the holes in a noticeable amount. Coolant leaked out of the side as the seal on the pump started to break, but not much out of the bolt holes.

That said, it only leaked while under pressure, not while sitting there. Of course, since I wasn't about to pull this thing apart AGAIN, I sealed everything I could.

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil

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rkj

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Earendil
After some silicone gasket sealer black on either side of the paper seal that comes with the pump, and some thread sealer on all the bolts, I now have a leak free engine! Woot!

Thanks guys. My self confidence in car mechanics has been restored, for better or worse

There ya go. Did you see if those lower bolts ran in to the water cavity?

I know that the lower left bolt does not. One can actually look inside and see (and feel) that there is a molded spot for the bolt on this car. If that molded spot was not there, the bolt would indeed sink into the coolant cavity and the bolt threads would be exposed. The middle right, I can't tell, and the top one I don't think would hit the coolant cavity.Also, if the top and middle bolts DO sink into the coolant cavity it would be very very small. I know that when I pulled the bolts that nothing came out of the holes in a noticeable amount. Coolant leaked out of the side as the seal on the pump started to break, but not much out of the bolt holes.

That said, it only leaked while under pressure, not while sitting there. Of course, since I wasn't about to pull this thing apart AGAIN, I sealed everything I could.

The reason no coolant came out when you pulled the pump was the coolant level was lower than the mounting hole on the bottom of the pumps mounting point or the hole through to the water cavity was plugged. Also, when you say "noticeable amount" that tells me right there you don't know for sure and did not run a wire through the mounting holes. Anyway, no big deal, I just thought you would put this to rest being you were right there.... whatever

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rkj

There ya go. Did you see if those lower bolts ran in to the water cavity?

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Earendil
I know that the lower left bolt does not. One can actually look inside and see (and feel) that there is a molded spot for the bolt on this car. If that molded spot was not there, the bolt would indeed sink into the coolant cavity and the bolt threads would be exposed. The middle right, I can't tell, and the top one I don't think would hit the coolant cavity.Also, if the top and middle bolts DO sink into the coolant cavity it would be very very small. I know that when I pulled the bolts that nothing came out of the holes in a noticeable amount. Coolant leaked out of the side as the seal on the pump started to break, but not much out of the bolt holes.

That said, it only leaked while under pressure, not while sitting there. Of course, since I wasn't about to pull this thing apart AGAIN, I sealed everything I could.

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rjk
The reason no coolant came out when you pulled the pump was the coolant level was lower than the mounting hole on the bottom of the pumps mounting point

Good guess, but I'm not that stupid ;-)
The first time I pulled the pump I had drained the coolant from both the radiator AND the block. If I had done that on the next 2 times, you'd be right. However since I had fresh coolant in the system I was loath to dump it out. So when I removed the bolts for the pump, the coolant level was actually well above the bolt holes, and was actually up around the level of the thermostat. Not the best way to go about things, but I had a huge catch pan, and at that point didn't mind getting coolant on my hands.

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rkj
or the hole through to the water cavity was plugged.

In which I wouldn't have a leak, now would I?

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rkj
Also, when you say "noticeable amount" that tells me right there you don't know for sure

In this case, it actually means that I chose my english carefully. It means that I did not notice any coming from the bolt hole in the pump. There was coolant starting to drip from around the edge of the pump where it "seals" against the block. I chalked that dripping up to the fact that I had just removed the bolt thus reducing the seal with the pump cavity. If there had been a decent hole between coolant resevoir and block bolt hole I would think I'd see coolant coming out of the water pump hole as well.

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rkj
and did not run a wire through the mounting holes.

That is correct, I did not. Without knowing the specifications on the depth of the drilled hole, and not being able to visible see where it might exit, I thought this would be an inconclusive test. But more than that, it was below freezing. I'll post a picture later of how the car looked before I started my work

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rkj
Anyway, no big deal, I just thought you would put this to rest being you were right there.... whatever

I actually kind of thought we already had. Some cars do, others don't. Even if I proved which side of the fence this IX is on, it would not disprove anyone's theory that some do, and some don't.

I know that when I pulled my 'i' completely apart to change the valve springs, that I did not seal any of the water pump bolts, and used the dinky paper gasket as I had on the previous two timing belt changes. And that block/head/pump/bolts were very clean. In fact probably too clean. The bolts probably should have had some sort of anti seize on them. I've never had a problem with that block ever leaking coolant

In any case, I will probably add a little gasket maker to each water pump I do from now on, and seal the bolt threads, just to be on the same side. It can't really hurt!

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Here is what she looked like before I took her all back apart on Saturday.





The hood is popped, that's why there is the gap, and the middle grill piece is removed. Otherwise, aint that lovely? It's sooooo much fun to start car repairs with a good bit of snow shoveling

Still, nice to see an ix in its naturally habitat, yes?

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Ahhh, youth. I remember when I used to do repairs in other than ideal conditions! Nice going on your success too. It's nice to finally sort things out, even if it does take a few trys.

Now, here's what I know to be true about that stinkin pump bolt thing. When I got my first thirty (I had someone do my 323 belt which was actually my first thirty) I had it towed to my shop, I wasn't taking any chances blowing the belt after I tested it. I took it down and was surprised to see coolant coming out of the pump bolt hole (this was on a 1986 325es) on one of the lower mounting holes. I made it a point to clean everything and seal all the bolts with a silicone sealer (that comes loose easy, not like loctite). If you have clean threads and use the sealer sparingly and don't over-tighten those small mounting bolts all goes well. Since then I've done quite a few 325's including my 1988 325is twice, It also had the same thing on the pump bolts (I'm pretty sure).

It would be nice to get conformation on this with others doing this job; I can't see the 2.5 being different, in this respect, than the 2.8 in any model form, two or four wheel drive.

Rick