On an E36 320i (105K miles), is it possible to check if the water pump has
the original plastic impeller or been replaced with one with a metal
impeller - without dismantling anything?
I can't see any obvious difference from the pictures at
and, as it's on the last dashboard light before the next service, I thought
I may as well get it replaced at the service if it's plastic.
No. You'll have to pull it off to tell. If you bother doing that you
might as well put the new one in, especially if yours is of unknown
mileage. Peace of mind is worth more than the price of a waterpump, IMO.
BMW now only supply a "new improved" plastic version. I was plenty surprised
last November (and pretty skeptical) when I opened the box at the BMW
dealers to find a plastic impeller on the new part! The faulty one I was
replacing was a metal type which had failed due to the bearing collapsing
(This pump was a replacement genuine part from 1997).
Mind you, this M50 lump in my old E34 had only had the original plastic
impeller (dodgy type) pump amd one metal replacment in 341,000miles when I
fitted the 'new' plastic type last year.
No E36 is safe. Waterpumps and radiators are maintenance items for these
cars, change every 75K miles. If you want a PREMIUM pump,, Stewart is making
a performance water pump for the E36. About $200 from several online
vendors. It's capable of higher flow and improved efficiency.
The upper plastic inlet on the radiator fails with age. Sometimes it just
breaks right off, leading to a loss of coolant accident, overheating, and
the resulting head warpage.
Even with stock parts, it's less than $250
Best? Best for what? There are OE or OEM replacement radiators, Baer,and
some others. All will work, most if not all will have plastic side tanks and
hose fittings. FluidDyne, PWR, Zionsville, and others sell custom all
aluminum replacements, some with 3 cooling rows. All of these will work,
there have been some fitment issues with some of these. There is also the
radiator from the MZ4 roadster that is a direct fit replacement. With a cost
of $150 to $750 How do you decide which is best?
FluidDyne is what I was thinking of. I beleive they make the one sold
by Zionsville too. Haven't heard of PWR before.
What I meant was that that the fully aluminum replacement by FluidDyne
was best if you are concerned about the logevity of the radiator. It
does not have plastic ends or hose fittings. Yes it costs more.
I agree. Reason I'm writing is that I just had a major cooling system
overhaul done on my 1998 E36 at 130K miles so this is still fresh in my
Based on my technician's comments (30+ years of experience) the only
reason the radiator necks break is because they've been overheated --
usually repeatedly -- by running the coolant level too low.
Of course, overheating can also be caused by a catastrophic pump failure
when the driver decides that "it should be okay" to drive a couple more
miles to the nearest gas station. And that's the absolute worst thing
you can do. If you hate the cost associated with a water pump
replacement, you'll really hate the cost of fixing a warped head. Rule
of thumb for BMWs -- if the temperature needle starts climbing toward
the red zone, pull the hell over NOW, turn off the car and call a tow
truck. Your checkbook will thank you.
The usual sign that the radiator is not long for the world is oval
(warped) necks...and possibly associated leaks, but as I found out,
simple wear and tear may not show up from the outside, which explains
why it's indeed a good idea to replace the radiator on some regular
interval. My tech found the plastic crumbling on the inside of the
necks, while the exterior looked like new. The necks could have broken
at any time.
If you follow BMW's guidelines on coolant flushes like I have, my car is
at least anecdotal evidence that the OEM components will last a very
long time. Based on my experience, I'd suggest 100K as a safe and
fiscally prudent time to do a pump replacement, but the funny thing
about touching the cooling system is that it usually makes a lot of
sense to replace everything else while you're in there (radiator,
thermostat/housing, hoses, belts, etc.) Parts cost more, but the labor
savings more than makes up for that.
Check out my site for more info including a close-up picture of the
currently-shipping composite impeller pumps. Click through:
Doug Vetter, ATP/CFI
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