Latest in Radiators?

[CMG]

I guess I've been into M3's for a while as it's time to do the coolant system. I did it completely back in 2008 and used Mishimoto radiator. I also used an OEM water pump, and that is what is now leaking and telling me it's time. I am pretty sure the Mishimoto is not leaking, but thinking about playing safe to ensure I can go another 10 years til the next time. I have used Behr Hella Service and OEM Behr, for the price the Behr Hella is worth it I can not tell the difference between the two. I could get another Mishi but saw that Koyo now has one for E36. I use Koyo for my Japanese cars and it's good stuff. Any recommendations?

[Pelican Parts]

I've also been a big fan of Koyo radiators and trusted them in my old JDM days. I say go for it. Let us know how it worked out if you pull the trigger on it. Lastly, I've included a link to our site's DIY tech articles in case you need some assistance during any maintenance or fixes down the line. Best of luck man!

BMW E36 DIY Technical Articles

[propcar]

CSF supposed to be good.

[th3turk]

I use koyo plus the Stewart pump, no complaints. When I'm putting around down the car is between 188F to 192F. Although I don't think the clutch fan will fit with the koyo, I run a spal set up


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[hli]

I'm running a CXRacing radiator I grabbed off of eBay for $120 shipped. Works great but but I do have a few small gripes. It did require a little bit of modification of the shroud mounting tabs to get everything to sit correctly, and the upper radiator hose inlet is also very close to the outlet that goes to the expansion tank so getting the hoses on was a bit of a challenge. I also needed to wrap the rubber grommets for the 2 upper radiator clips with duct tape so they wouldn't move around too much, CXRacing oversized the recess the grommets are supposed to sit in.

But if your Mishimoto is working fine, why replace it? Just use it until it breaks.

[hc1001]

I also agree in reusing your Mishi if it isnt leaking. If you are the original owner and if it has a leak, you can warranty it with them.

I had mine for about 8 years until i upgraded to a Koyo. The quality of the Koyo is really nice but if there is any failures or defects, there is no warranty unless you report it during the first installation. My Mishi didnt have any leaks but the Koyo has a bigger capacity and thought it would be better for cooling since i track my car. I havent really noticed any difference between the two. Im sure the Koyo keeps things slightly cooler but the Mishi was fine when i had it also.

[CMG]

I've done a lot of work on the car and had every possible coolant system failure I think (radiator neck, water pump, triple nipple in firewall, etc.). Never had overheat issues and I haven't even been using mech fan. Not gonna do electric fan, not worth it for this car IMO. I already modified the shroud and everything when I first put everything in, fits like oem, but it has always been bigger and more loosely seated than the stock one, the top mounts are too big, pennies work for spacers. The Koyo has a 48mm thick core, so will be more thin which is a good thing in this case IMO. Eventually when I have time I will probably do the self bleeding euro reservoir set up (way better for checking coolant level IMO). Has anybody used the Stewart water pump and/or mishimoto radiator for more than 10 years without any issues? I do see what could possibly be seepage on the end tank welds, but I would have to keep an eye on it for a bit to verify, and I can't drive it with the water pump leaking. I probably could do the water pump as is, and keep an eye on everything else to see how it does. Is Stewart the only one with metal impellers, there has to be a cheaper alternative?

[th3turk]

Stewart is not the only one with a metal impeller, but it is arguably the best one and the only one that will most likely out last the car. You cannot go wrong with the Stewart pump, seriously. Well worth the premium over the other pumps.


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[hli]

The revised composite OEM water pumps are supposedly the next best option. The Volvo people have also run HEPU water pumps for something like 150k with no issues if I recall correctly, but I'm not sure of their longevity in an E36 application. I don't think the Stewart is worth the price, there are plenty of other options unless you plan on milking the lifetime warranty over the next 25 years.

[LockDots]

The revised composite OEM water pumps are supposedly the next best option. The Volvo people have also run HEPU water pumps for something like 150k with no issues if I recall correctly, but I'm not sure of their longevity in an E36 application. I don't think the Stewart is worth the price, there are plenty of other options unless you plan on milking the lifetime warranty over the next 25 years.

Not worth it for a lifetime warranty and increased flow? I'd say that's worth the assurance for an already weak cooling system.

[pbonsalb]

I have been running a Stewart pump for 10 years. Been in 3 different motors.

[hli]

Not worth it for a lifetime warranty and increased flow? I'd say that's worth the assurance for an already weak cooling system.

You can pretty safely do 80k on any of the OEM equivalent pumps, and they run about $50 each. Realistically you wouldn't need to change the pump more than 3 times before the engine is going to need other work anyways, so if you don't mind spending the extra hour or so getting the waterpump out while doing a cooling system refresh I'd say it's still cheaper and just as reliable as going with a Stewart.

Yes you do get increased flow with the Stewart but the stock cooling system performance wise is just fine. It just needs to be refreshed every 80k or so. All of this is just my personal opinion, I can also see how someone would want the peace of mind and the ability to not have to muck about with swapping cooling system parts often.

[ScotcH]

I have been running a Stewart pump for 10 years. Been in 3 different motors.

Yup ... buy it once, and forget about it.

[tiMASTER]

My stewart pump is pushing 15 years now I think. Never an issue, and I have the engine driven clutch fan on it as well. That added weight/load can speed the demise of the stock pump...

[Eddie916]

Mishimoto's warranty is great. However, I did have 2 of them leak within a year of installing I believe.

- - - Updated - - -

That said, I now have their extra thick e36 one and it's probably got a 3/4 inch thicker core

[CMG]

Thanks for the info. Sounds like people are happy with Stewart and have used them for long periods of time, I didn't realize they also had a lifetime warranty. I could care less about increased flow but no disintegrating impellers and no leaking is what I am after so sounds like a good choice. I have both the genuine OEM and Hepu water pumps, and IMO they are the same thing but $100 difference. The water pump in it now is the newer oem version so we'll see what the impellers look like once it's out. When I did the coolant system on my other M3 I did it preventatively with no issues beforehand, but discovered the w/p impellers were falling apart (free used water pump anyone?)The engine should not need any work for many years, it was fully rebuilt less than 20k ago.

[TH3 Shifty]

FYI Saleri makes the OE BMW composite water pump

[Gene V]

FYI Saleri makes the OE BMW composite water pump

This is what my independent shop uses...

[CMG]

FYI Saleri makes the OE BMW composite water pump

Yeah I could be mistaken on the name. I thought I remember Hepu being oem equivalent. Either way definitely getting stewart for starters. Looks like $165 shipped is cheapest I can see.

[pbonsalb]

My stewart pump is pushing 15 years now I think. Never an issue, and I have the engine driven clutch fan on it as well. That added weight/load can speed the demise of the stock pump...

I bought the year after Stewart made the pump, and I bought in 2006 or 2007. So I don't think 15 years is possible. 12 at the most.

[CMG]

I ended up doing full coolant system refresh with belts and pulleys. I used the Stewart pump and a CSF radiator and everything else was oem. The only other non oem part I used was a water pump pulley. Apparently Uro is the only company that sells metal water pump replacement pulleys rather than composite, so although Uro is usually trash this might be one item of theirs that is ok.
I guess I've been into these cars long enough to have gone through multiple maintenance periods so guess I'll share my experience regarding long term coolant system maintenance. The miles I drive per year are below average, but it is in a hotter climate, and I definitely drive the cars hard. I think that while my maintenance interval is around every ten years, for many people it may be closer to every 7 or 8 years.
-Other than a coolant hose or heater core popping a leak somewhere, there are 3 common coolant system big fails IMO:
-1 is the water pump. Always use metal impellers not composite. Even the OEM composite water pumps WILL fail and fall apart given enough time. Metal water pumps can also fail at the bearing and get loose, allowing water to leak out. If you wanna do it cheap you can use Hepu, and if you want to do it right get the Stewart.
-2 is of course the radiator neck. There are lots of cheap options like Hella, Behr, E46, etc. but as before any composite end tanks run the risk of falling apart over time. You can get a Behr Hella service radiator for under $150, and replace it every 5 years or so, or for maybe twice that much you can get a direct fit aluminum one that can possibly last the lifetime of the car.
-3 is what I call the triple nipple. It is a little plastic fitting connecting the 3 engine hoses into the one heater core intake in the firewall on the driver side. In the same way that the radiator neck can break this can break leading to massive coolant loss. At this point in our cars age I would say that it's a consideration to possibly do on any car.

-The best way to prevent a failure is preventative maintenance, and to do the whole complete system at least every 10 years (some stuff can be re-used, depends on owner discretion). If you don't know when your car last had it done you can look for dates on the radiator or hoses to see how old they are.
-The bare minimum way is to ensure your water pump has a metal impeller, and to make sure radiator is new or aluminum.
-Some aftermarket brands are same as OEM (depends on particular item): Behr, Rein, Meyle, Lemforder. Only OEM coolant reservoir should be used.
-Ensure all parts are mounted properly and secured. In some cases there is less than 1cm clearance between fan and shroud and hoses. Loose attachments and mounts can cause it to catch and grenade. Bad motor mounts or water pump bearing can cause enough shift to do this. The stock top radiator latch mounts kind of suck but they are the only easy option.
-A well maintained and fully functional coolant system should not have any issues whether it's bumper to bumper traffic or on a racetrack (I also went a couple years without a clutch fan and no issues). It's a real finicky coolant system and I believe I have had to take care of every possibly coolant related failure I could think of. Even though it sucked having to deal with it in a way I was really lucky. For example years ago I had just pulled off the freeway and was sitting at a light and I saw some steam coming up, then as I started to pull over and park the gauge started to move up. When I had the triple nipple bust on me it was like a human getting a bust aorta, straight instant coolant dump, but luckily I was only a short distance from the house and was able to turn it off and coast. Bottom line is if you see or smell coolant, or temp gauge starts to move at all, pull over and park ASAP and check it out. It will go from middle to red in less than a minute, and red can quickly lead to engine issues.

[adamnur]

Good advice and information overall, hopefully it helps someone in the future. However, I don't see a reason not to run a composite impeller pump, depending on manufacturer. The old full plastic ones, sure, failure rate is evident. However, the composites last and have proven to be a good revision over the plastic. Saleri makes BMW's OE one, which I'm running and have been for 5 years. My original pump was still working fine when I replaced it with the Saleri, so I had that in for 13 years (1999 M3).

Unless there have been many composite impeller failures I'm not aware of.

[ben4bama]

I know of Stewart pumps failing so they don't last forever

[bluptgm3]

I have been running a Stewart pump for 10 years. Been in 3 different motors.

Yup ... buy it once, and forget about it.

My stewart pump is pushing 15 years now I think. Never an issue, and I have the engine driven clutch fan on it as well. That added weight/load can speed the demise of the stock pump...

I know of Stewart pumps failing so they don't last forever

Stewart pump uses essentially the same bearing/same size bearing as the stock pump, no added life here. Mine lasted ~100K before bearing failed. The warranty is Limited to one year.

Stewart is not the only one with a metal impeller, but it is arguably the best one and the only one that will most likely out last the car. You cannot go wrong with the Stewart pump, seriously. Well worth the premium over the other pumps.

The added benefit of the Stewart is the shroud (similar to M42/M44 pump) around the impeller and the design of the cast/machined impeller which improves the pumping action. This shroud also stabilizes the pump shaft when the bearing does fail and helps prevent total seal failure.
The thin gage stamped stainless steel pumps probably come in a close second (1999 OE pump, similar to current Hepu, and now Graf).
I question the efficiency of the thick vane cast aluminum impeller pumps. (Graf, URO, and others)
So no, not all metallic impeller pumps are the same IMO.

[CMG]

I have had both old version and new version OEM composite pumps both fail, and grenade (sometimes you won't even know it until you take it out). I have also had metal water pumps get a bad bearing and start leaking. Bluptgm3 is correct that the main difference for the Stewart is a support shroud around the impeller to give the impeller support so the bearing doesn't carry as much load.