2008 135i Fan Blowing Hard and Engine Warning

[ctrzaska]

Hey all-

Have an 08 135i Conv and a few issues just popped up. Car sputtered a bit yesterday and the fan was seemingly on max… yellow engine light popped on and I limped the mile home. Engine HOT.

Today startup was spotty, and rpm jumped to about 1500 for a bit (odd) until simmering down to about 750, light on after a few minutes and the fan on hard a few after that.

Pulled codes from a basic reader (all I had) and they were fuel related and not permanent. While running, noticed the hose in blue was cold, and the one in red hot as hell. No idea why. Thermostat replaced a year ago, though who knows. Water pump about to go? Any other ideas? Thanks.

[Lester]

Water pump.

[ctrzaska]

Originally Posted by Lester

Water pump.

That's my fear, particularly right at a holiday weekend.

[tracer bullet]

Almost guaranteed water pump. I give it a 95% chance. Maybe 96 - 99%.

Look for a procedure to bleed the system, you do a key in the ignition (but car not started), hold the gas pedal kind of thing. It'll cycle on and off, that's normal. But mine was whiny as hell, super loud. If yours is anything but almost silent, that's your issue.

The fan maxxed out and sudden temp swings is the give-away.

[zx10guy]

Originally Posted by tracer bullet

Almost guaranteed water pump. I give it a 95% chance. Maybe 96 - 99%.

Look for a procedure to bleed the system, you do a key in the ignition (but car not started), hold the gas pedal kind of thing. It'll cycle on and off, that's normal. But mine was whiny as hell, super loud. If yours is anything but almost silent, that's your issue.

The fan maxxed out and sudden temp swings is the give-away.

And pop open the coolant reservoir cap and look inside. If the coolant stream is weak, then it's also a sign the pump is not working correctly.

[ejm3]

Another vote for water pump.

[ctrzaska]

Originally Posted by zx10guy

And pop open the coolant reservoir cap and look inside. If the coolant stream is weak, then it's also a sign the pump is not working correctly.

Coolant stream is definitely dodgy.

[ctrzaska]

Thanks, all. Ordering a water pump and thermostat kit today.

FWIW, CEL is now on consistently and tossing the following codes:

[Lester]

Yes, it will be the water pump. Once it fails, the electric fan kicks in due to overheating. It doesn't really help much. The engine will eventually shut down as the coolant is not circulating.

[ctrzaska]

New water pump and new thermostat two days ago, and still the same issue. Sputters with a VERY rough idle at startup, sometimes with the fam kicking off on high soon after, sputters a bit occasionally when driving (almost like with a bad coil— but they're new) and the CEL and engine lights both pop on with the fan in overdrive. After a restart usually starts up ok with no lights. (AC now cold as hell FWIW.).

Going to pull the codes again the next time the CEL goes off, but this is sounding fuel-related if maybe unrelated to the fan? So odd.

[ctrzaska]

Throwing the following codes, the last one pending: P302C, P15DF, and P142E. Now, could mean fuel pump, et.al., I guess, in addition to something still amiss on the cooling end?

A check of the coolant shows the correct level and nothing burped up. The cooling hoses after running it for a bit are, however, oddly back to being hot on the driver side and cold opposite as in the initial pics.

Bizarre.

[tracer bullet]

HPFP (high pressure fuel pump) is a thing for us, but more so on the earlier years. Your 3 codes all seem to imply fuel pressure issues and that could be the cause.

You may have 2 things at once, fuel and coolant issues. Your initial post certainly implied the water pump, and of course it is super common for us and so it wasn't hard to assume that was the cause. It may have been somewhat missed that you had fueling issues at the same time.

As for the new water pump, there's a chance there's an issue with the installation, but somewhat unlikely. Any chance a connector wasn't plugged in? Does it definitely seem to run i.e. the bleeding procedure works? You won't get a crazy strong coolant flow, it'll come and go as the pump cycles, and it's shooting out of a smallish port. If it appears to be OK right now, I'd just focus on the fueling issues and see if the hose temperature mystery resolves itself.

As for the fueling issues, I'd guess HPFP, but you'd want to do some research and see how to test it to be sure.

[zx10guy]

Agree with Tracer. Go through the bleed procedure to see if the water pump is behaving correctly. When mine was replaced, the new one failed almost immediately. The failed replacement was a genuine BMW part. Another OE pump was installed and has been fine since.

[ctrzaska]

Thanks, all. Coolant appears to be ok, and with no leaks etc., but could be a pump issue regardless, and in theory I suppose could be faulty regardless (new Conti pump, but who knows). Will bleed everything and give it a full run through on Monday. I tend to agree with the fuel issue being separate, though I'm in the car now and no hesitation, no warning lights, no nada.

Having owned a Land Rover Series II Disco, an E46 I beat the life out of to almost 200k, and with 200k on a 911 that had seen every issue known to the 996 it seemed, I'd thought I'd seen it all. Nope.

Thanks again. Will keep everyone posted.

[tracer bullet]

Originally Posted by ctrzaska

I'm in the car now and no hesitation, no warning lights, no nada.

OK, well, that's good to hear but crazy.

How's your battery? How old? Maybe consider a bench test for it, be sure it's good (not just voltage but amps and capacity, etc.). Another common thing for us is that if the battery starts going bad, all sorts of random, dumb fault codes begin to appear that have nothing to do with the battery. Guessing low voltage to the various sensors or ECU itself (plural) starts confusing things.

[ctrzaska]

Originally Posted by tracer bullet

OK, well, that's good to hear but crazy.

How's your battery? How old? Maybe consider a bench test for it, be sure it's good (not just voltage but amps and capacity, etc.). Another common thing for us is that if the battery starts going bad, all sorts of random, dumb fault codes begin to appear that have nothing to do with the battery. Guessing low voltage to the various sensors or ECU itself (plural) starts confusing things.

Aaaand… haywire all today so far. Losing power, clearly not getting fuel, and fan on overdrive. Odd that it seems to be concurrent all the time as these shouldn't be related, theoretically, at least in my mind.

Plan is to bleed the system tomorrow AM and separately check the fuel issue. From there, who knows.

Battery hasn't been checked, but I'll toss a voltmeter on there tomorrow and see what it returns. Thanks for the suggestion.

[tracer bullet]

FYI it's more than just measuring voltage. It's an indicator but not the whole story. I'd get a real test done, or find a good DIY that has a lot of steps and checks.

Can't vouch for this one but as an example: https://www.wikihow.com/Load-Test-a-Battery

[zx10guy]

Yeah, a volt meter won't tell you the true state of the battery. You'll need to have it tested. Most parts stores will test the battery for free if you bring in the battery. They might even test the battery in the car if you drive the car there.

I made the investment to add a battery test module to my Thinktool Pros scan tool so I don't have to deal with going to a parts store to have my batteries tested.

[ctrzaska]

Fired it up just now to take it in and have a full battery test done (load, etc.— thanks for the advice), and it's doing what it's been doing on very cold starts—> very bad rumble, barely tops 500rpm, give it gas and rpm remains erratic, leaps to almost 1500 for a few seconds, then the engine light (big one, not CEL) right after fan kicks on at max speed. I get the fact that there's some sort of fuel issue, but no idea at all why the fan would even be a thing.

[ctrzaska]

Ignition off then back on a few min later, and while sounding a bit gravelly and with a slightly rough idle, it's fine.