Author Topic: New thermostat, rough start and humming (Read 5515 times)

Sarstan · « **on:** February 11, 2011, 06:23:04 PM »

Just installed a new thermostat in my car since it barely got above the blue area in the temp gauge. Now the car takes a few seconds to get into proper idle when starting and it doesn't like to idle after coming to a stop. Similarly, I've got a humming sound coming from what seems to be near the throttle (or just the top of the engine in general).

I had neither problem before and swear I didn't mess with anything but the thermostat housing and the thermostat. I may have not properly drained/flushed/refilled the coolant, but can't see why that should make a difference. No leaks or anything of that nature. Any ideas to get me going on this hunt?

DesktopDave · « **Reply #1 on:** February 11, 2011, 07:09:35 PM »

Good question. Maybe a vac leak from moving stuff around? Does the car warm up properly now? Bleeding the cooling system is a PITA usually.

Sarstan · « **Reply #2 on:** February 11, 2011, 07:20:25 PM »

I looked around for a vac leak and haven't found any. As far as the cooling, I may well still have not done it properly. The manual I have is relatively vague about how to do it and I've been uncomfortable about it since I only see one cap, not two for a reservoir and the radiator itself. I honestly have never been so confused than with working with the cooling system. The system seems to be warming up properly now, but I haven't wanted to run it to operating temperature until I find out what the humming is.

DesktopDave · « **Reply #3 on:** February 11, 2011, 07:36:43 PM »

I park mine up a slight grade and water the mix down to 66/33 water/coolant. I also pull the main hoses & fill them both before the final bleeding. The only bleeder in the system is that fragile little screw in the radiator tank by the fill cap. The expansion tank is integrated into the radiator; that bleeder is the only way to get the air out when it's hot.

BTW, that bleeder has a cross pattern...but use a fat straight-bladed screwdriver. A philips-head will break the top off the threaded screw and cause a 6' vertical stream of scalding hot coolant. Don't ask me how I know.

Sarstan · « **Reply #4 on:** February 11, 2011, 08:02:01 PM »

I'll try bleeding the system again. I've tried to use that before, but I have a feeling I can do it better than how I did.
Who knows, maybe that's all it needs to be done. I did notice that the fluid level has dropped since last running it, so that could well be the issue.

Sarstan · « **Reply #5 on:** February 12, 2011, 01:15:24 PM »

I noticed that my Haynes Manual tells me to fill the radiator, then fill the reservoir to the cold line. The thing is there's only one cap over the reservoir. Am I missing a way to fill the radiator? Or do I just fill the reservoir constantly until it stays at the line?

pdxmotorhead · « **Reply #6 on:** February 12, 2011, 02:08:13 PM »

use one of the water treatments like Water Wetter form Redline or Blue Ice, it breaks the surface tension of the coolant and causes the air to flow out of the system.

I've never had a bit of trouble bleeding the car if I used the redline....

Dave

Sarstan · « **Reply #7 on:** February 12, 2011, 02:22:41 PM »

It seems I just wasn't following the instructions properly. I finally got it bled. The car gets to just a hair under halfway and stays, which is used to be just over blue, so that must be good.

I still have this wonderful whining sound coming from the engine or perhaps near the throttle and stumbling idle (which isn't really bad, but it does make the car vibrate nicely). I changed my spark plugs and took a look inside to see if there was any issue on top of the pistons. Just the usual caked on crap. For a bit I was concerned I had a blown head gasket, but haven't seen any signs of it.

Not sure what to check at this point. The only hose that I think I could have bothered was below the air intake boot, but I made sure that was in.

DesktopDave · « **Reply #8 on:** February 12, 2011, 02:55:51 PM »

That line under the intake boot was split nearly in half...falling off the 90deg elbow it was on. It made a bit of a difference once I fixed it, but the motor is no quieter. The M42 just seems like a loud motor anyway.

Sarstan · « **Reply #9 on:** February 12, 2011, 03:06:22 PM »

Mine slides right off the elbow as well, so I think I'll have a second look at that hose. I also realize I took off a bolt near the front of the engine (which I thought in Zoso's write-up was stating was the coolant drain). Turns out it was some sort of 4 inch long bar coated in oil and the bolt was a cap that came off this bar. I was (barely) able to get it screwed back in, but now I'm wondering if maybe bothering that has anything to do with it.

It was 19mm, passenger side, in front of the exhaust header. Not sure what exactly it was for, but now I'm concerned about it.

Sarstan · « **Reply #10 on:** February 12, 2011, 05:21:11 PM »

Went ahead and took the car half around town. The temp stayed properly, the car only has idling issues at the start (hot or cold, it "bounces" a couple of times then levels). I sprayed out the ICV and got a good bit of gunk out of the air intake. Still, nothing has stopped the whining sound. I suppose if anyone asks I'll say it's a supercharger or turbo. More or less what it sounds like.

DesktopDave · « **Reply #11 on:** February 12, 2011, 05:27:15 PM »

M42 coolant drain is on the exhaust side rear of the block roughly under the cyl #4 header. It's a very short 17mm bolt IIRC. Hard to see, really.

Are you saying you took a hex head plug off the passenger side of the motor? Near the front? If it came out of the alloy part on the front of the motor (timing chain case) that 4" long bolt might have been your timing chain tensioner...in that case double check it...that whining sound might be your timing chain self-destructing. Before you panic let's take some pics & make sure. You might have to take it back out again.

Here's a thread with what I think might have happened:
http://www.318ti.org/forum/showthread.php?t=21835

Here's a pic at r3v...check out post #5. The little bit on the upper left side of the block is the timing chain tensioner. It has a spring, fills with oil & keeps the timing chain nice & tight. If it's overextended, the chain will eat one of the guides & you'll suddenly wish you had a different car.

I'm cooking dinner right now, I'll get right back to you. Don't drive the car until we get this squared away. I'll share the recipe if it turns out OK...it's "Daddy's trying something new" night here at Casa la Dave so it's about a 50:50 chance.

DesktopDave · « **Reply #12 on:** February 12, 2011, 07:28:53 PM »

Well, the green sauce worked out just fine. Here's the recipe:

Ingredients:
1 pound of broccoli
4-5 cloves of garlic
1/2 onion
1 can soup concentrate
1 pound pasta.

Directions:
Boil the broccoli, garlic & onion. Once soft, pull them out with a strainer or slotted spoon, place in blender (reserve the water for the pasta). Add the can of soup, blend until very well mixed.

I'd recommend a string pasta like fettuccine or spaghetti. Boil pasta in the reserved water until al dente. Serve with grated parmesan or romano, serves 3-4.

DesktopDave · « **Reply #13 on:** February 12, 2011, 07:36:31 PM »

BTW, if you get a chance go out and determine that you did pull the tensioner, I'd recommend a new one or draining the oil out of the old one so it can re-adjust.

I don't mean to insult, so if you've heard this before just ignore it. The spring extends the tensioner until the chain is at proper tension. However, if the spring alone had to hold the chain, it'd let the chain stretch back and forth between accel & decel, affecting the cam timing. So the tensioner body has a port for pressurized oil. The oil fills the body of the tensioner preventing it from retracting. A tensioner should never be installed when filled with oil. If you've pulled the tensioner and now it's a bit too long, you're bending the chain guide and the chain is eating it.

This will cause you trouble, if it's too tight. The chain will strip out the chain guides and/or eat the motor's front case rapidly, like within a few hundred miles.

You can pull the tensioner apart & drain the motor oil. Put it back in & you should be able to compress the 19mm cap enough to install it. The car will clatter like nobody's business for a little while, but should quiet down in a minute or two. Don't rev the motor unless you have a new tensioner installed and you've installed it compressed.

Sarstan · « **Reply #14 on:** February 12, 2011, 09:51:34 PM »

Heh, I had a feeling I pulled out something that should have been mentioned early on. I did get that exact same "bolt" out. I didn't think of it too much, but it was a nightmare to get back in. Lots of pressure and had to wedge a hammer handle between the frame and the ratchet with bolt in place to get it to finally screw in.

No problem telling me about it. The engine is a big no-go zone for me. I have only opened one engine up to change a head gasket which ended in a mess anyway (it was a junked car to begin with). Anyway, long story short I need to drain the oil, pull out the tensioner, wipe it off, then stick it back in before putting the oil back in? I think I need to change the oil anyway so now it gives me a great excuse.