Knocking sound...?

[Jim Lepage]

Hi. When I purshased my E30 it has a knocking sound coming from the front when it was on heater and not on cold air setting. Today I changed my blower resistor and now the knocking sound can be hear anytime. It's knocking only when I r3v the engine and more I r3v, more it's knocking. It's starting at about 2000 rpm. It's doing toc toc toc and if I put my hand beside the gas pedal on the tunnel I can sense something banging.

What could do it ? It's a 1991 318is with M50B25 swap.

I also replaced the intake boot but I don't think its the problem. The old one was cracked

Thanks and sorry for my bad english... :?

[Jim Lepage]

I looked further and the sound is coming from the internal heater box. Now what can do that sound and why it's going faster if I r3v the engine ?

[Jim Lepage]

No one can help me ?

[rkettner]

i know its hard to translate from french but this problem is quite vague.

make a video of the sound and post it on you tube for everyone to view.

[Jim Lepage]

i know its hard to translate from french but this problem is quite vague.

make a video of the sound and post it on you tube for everyone to view.

I don't have video camera. I'll try to explain it better.

My E30 have a sound (toc toc toc) coming from the heaterbox (under dash big black plastic box). It's coming only when I r3v my engine (2000+ rpm). If I put my hand on the heater box when the sound can be heared, I feel something banging inside the box.

I'm wondering what can do that and why it's doing that only when I r3v my engine ?

1991 318is with M50B25TU swap. It was doing that only when i putted it on warm setting control but since I changed the blower resistor it's always doing it (on cold and warm setting).

Tonight I'll try it with the old resistor.

[Jim Lepage]

Ok I found that is knocking on the heater core side. It's knocking a lot. My heater box bottom housing is cracked on this side. I also found that if I put my control to warm, a little smell of prestone can be detected. I looked and didn't find any trace of liquid on my floor.

What should I check now ? Heater core ? Water valve ?

Please help me.

[hendrixvodu]

do you have a junk yard in your area? id just pull that whole box and replace it....probably pieces of plastic or something in there

[Jim Lepage]

Tonight I'll check the recirculation stuff.

http://www.e30tech.com/forum/showthread.php?t=59413

[StereoInstaller1]

Is the car overheating?

I think you might have severe bubbles, making a "hammering" sound, like in an old house with shitty plumbing.

You say you smell coolant? Are you losing coolant?

[Jim Lepage]

Is the car overheating?

I think you might have severe bubbles, making a "hammering" sound, like in an old house with shitty plumbing.

You say you smell coolant? Are you losing coolant?

It's not overheating. I looked and didn't find any coolant on my floor. Tonight I'll check for bubbles in my system. It was one of my option.

[StereoInstaller1]

I can't imagine how severe it would have to be to make a hammering...either way, post what you find, OK?

[Farbin Kaiber]

I guess i'm understanding, or maybe not. So it's not a blower speed specific noise? Does it change when you change any of the settngs for you climate control system?

[Jim Lepage]

I guess i'm understanding, or maybe not. So it's not a blower speed specific noise? Does it change when you change any of the settngs for you climate control system?

No, It's always doing it. From about 2000rpm to 3500rpm. It's really weird.

[lordofthewaters]

If you've got a cracked core, you'll want to bypass it anyway, so why not just connect the two heater hoses and see if the knocking goes away. Sounds to me like there's something in there that's moving around when the coolant circulates.

[Jim Lepage]

If you've got a cracked core, you'll want to bypass it anyway, so why not just connect the two heater hoses and see if the knocking goes away. Sounds to me like there's something in there that's moving around when the coolant circulates.

Yes I was planning to bypass it. It's a summer car anyway.