Mike's Alpine White 1991 318is

[mike.bmw]

I'm thinking that my thermostat is stuck open. When I bought the car in March of last year the coolant temp gauge would be steady at the 12:00 position. Over the past months I've noticed that the coolant temp never seems to the 12:00 position, even after a long drive. Here's the coolant temp after a 12 mile commute in 43 degree weather and idling in a parking space for a few minutes:



I guess the gauge itself could be faulty. Or perhaps the coolant temperature sensor. I recently replaced the SI board, which can cause gauge issues, but these symptoms exists prior to that. My gas mileage has been about ~22mpg (both before and after chip installation), so the car may be running slightly rich due to the lower coolant temp.

Thoughts on other possible causes/issues?

To replace the coolant hoses coming off the thermostat, the thermostat itself, o-ring, gasket, new housing bolts (just because), and BMW coolant it looks like it will run about $120-$130 in genuine BMW parts. I'm feeling a bit lazy so I may call a local/trusted shop to get an estimate. I've read a few tutorials (http://zoso.no-ip.org/318i-thermostat.html) and it doesn't look like a hard job. Certainly easier than replacing the "mess under the intake". I'd rather not clean up the inevitable coolant spill off my garage floor though ;) . If I a labor quote of many hundreds of dollars I'll just do it myself.

[Eric Giles]

Mike, my car has had the same issue since I purchased it, and I am certain that the thermostat has failed open. I have all the parts, I just have to find time to tackle it. With all you have already done, you can easily handle it yourself.

[squidmaster]

The worst part about doing coolant yourself is disposing of it properly. Stuff is insanely poisonous and harmful. There are always a couple of jobs that I take to a proper shop, like coolant and AC draining.

[mike.bmw]

Mike, my car has had the same issue since I purchased it, and I am certain that the thermostat has failed open. I have all the parts, I just have to find time to tackle it. With all you have already done, you can easily handle it yourself.

The worst part about doing coolant yourself is disposing of it properly. Stuff is insanely poisonous and harmful. There are always a couple of jobs that I take to a proper shop, like coolant and AC draining.

I'm still waiting on one more estimate which I should receive today. The estimate I received yesterday was $740. Yeah. Wow. Granted shops have the expected markup on parts, but based on what I've read this seems like a 2 hour job. So even at double the parts cost, that's a lot of labor time.

If the other estimate is astronomical, I'll do it myself. Plus that will give me a chance to really clean the front of the engine and determine where my minor oil leak is actually coming from. I don't have any 32mm wrenches to break the fan loose (reverse threaded), but I did find BMW fan removal tools on amazon for $20 shipped, so I'll likely pick up a set of those. I'm assuming these will probably work even though it doesn't specify M42?

https://www.amazon.com/Clutch-Wrench-Water-Holder-Removal/dp/B017VLLQ6M/ref=sr_1_fkmr2_1?ie=UTF8&qid=1487766452&sr=8-1-fkmr2&keywords=m42+fan+removal+tool

I'll likely buy a new thermostat housing as well. It's less than $50. I'm sure the original housing on the car, which still has cosmoline on it, is degrading around the mating surfaces.

There are certain jobs that I will take to a shop. Generally because I've done them a number of times and don't really enjoy them, plus the cost of labor is relatively cheap. For example, I don't enjoy bleeding brakes (even using a power bleeder that makes it a 1 person job). I'll gladly pay a shop $60 to bleed my brakes. Good point on disposing of the coolant properly. That reminds me I need to research where to take that. The local auto stores won't take it, but perhaps there's a hazardous waste disposal facility in my county.

[jeenyus]

it could just be that the needle is loose and you need to tighten it. I'd check that before you just into buying a new thermostat.

[mike.bmw]

it could just be that the needle is loose and you need to tighten it. I'd check that before you just into buying a new thermostat.

The gauge needle? I can double check that, but the gauge does start out in the correct position when cold and it moves up/down depending if I'm sitting in traffic or I'm on the highway. The radiator hoses do warm up, but there never get as hot as I'd expect.

[WestCoastEta]

Ugh coolant is the worst. What a mess.

You might want to check local bicycle shops for that 32mm wrench. I found one at a bike shop less than a mile from my place.

[jdt10768]

Are you certain that the brass nut is tightly screwed onto the back of the cluster?
If it's loose, can cause bad readings and jumping needle

[mike.bmw]

Ugh coolant is the worst. What a mess.

You might want to check local bicycle shops for that 32mm wrench. I found one at a bike shop less than a mile from my place.

Yeah. I'm not a fan of cleaning up coolant off my garage floor. Or transporting it for proper disposal. Though in the past I've used emptied gallon water jugs for transport and it has worked out nicely.

Are you certain that the brass nut is tightly screwed onto the back of the cluster?
If it's loose, can cause bad readings and jumping needle

I'm not certain it's tightened. I did have the cluster out recently to replace the SI Board, but I didn't check the 7mm nuts. From what I've read, a loose fuel gauge nut would result in a jumpy needle and/or large reading swings. My coolant gauge is operating smoothly, it just hasn't gone past the the tick in the photo I posted earlier. If I find some time tonight I'll pull the cluster and check that nut before I start ordering parts (or schedule something with a shop).

[jeenyus]

The gauge needle? I can double check that, but the gauge does start out in the correct position when cold and it moves up/down depending if I'm sitting in traffic or I'm on the highway. The radiator hoses do warm up, but there never get as hot as I'd expect.

Even with a lose needle it could read accurately to a degree (pun intended) but it's worth checking before you go spending money. Mine works right up till midpoint then it goes crazy.

[mike.bmw]

Even with a lose needle it could read accurately to a degree (pun intended) but it's worth checking before you go spending money. Mine works right up till midpoint then it goes crazy.

Good pun!

I pulled the cluster and checked the gauge and nuts on the back. Everything seemed good and I verified all was tight / connected.

[mike.bmw]

Good times in the garage tonight (not really). I've pulled the cluster 3 times now.

After checking the coolant gauge nut the first time and reinstalling the cluster, the speedo now reads about 10mph higher than GPS speed.

I installed my donor cluster and swapped the coding plugs. The donor cluster reads the correct speed compared to GPS.

I've taken my original cluster apart, but it's not obvious what/where the issue might be.

Update: I used a compressed air / duster can on the original cluster and reinstalled it. It's back to normal now. Also, the donor cluster had the exact same reading on it's coolant temp gauge as my original cluster which leads me to believe it's not a faulty gauge.

[mike.bmw]

M42 Reseal
After thinking about the thermostat replacement for a few days I decided to have a shop perform the work. While the car was at the shop I asked that they take a look at the oil leaks (upper oil pan and upper/lower timing covers) and compare the leaks to what they saw 1 year ago during the post purchase inspection.

I got a call this morning and the shop confirmed the oil leaks had indeed gotten worse. Mind you it's nothing that would hurt the engine or prevent me from driving the car, but there's a solid coating of oil over the bottom of the engine and I've been seeing more drops on the cardboard under the car overnight. It's something that would likely need to be addressed sooner than later. It bothers me that the engine leaks. :)

So I decided to hold off on the thermostat replacement and have it done in conjunction with the timing cover gaskets, oil pan gaskets, and crank seal a couple weeks from now. They'll have a look at the timing chain and guides while they've got it apart.

It's not going to be cheap, but it's going to give me peace of mind. I plan on hanging on to this car for a long time. And with the amount of money I've been dumping into it, I better hang onto it for a long time. :)

Phantom Codes?
In other news I've been trying to track down a phantom "Ignition Coil #1" code. No check engine light, but the stomp test reveals 1271. I need to find some time to find a spare DME and swap it into my car to see if it's DME related. I started a thread on the M42 subform here with what I've tested thus far: http://www.r3vlimited.com/board/showthread.php?t=402849

Accomplished Goals?
A couple months ago I said this:

Other stuff!
So here's an updated list of things I want to accomplish in the next 2 months:
- LSD with fresh bushing (and possibly fresh seals)
- fresh IS front valence + paint
- fresh IS rear spoiler + paint
- obtain and install working/refurb'd SI board
- Replace seat shocks. Clean/lube seat-back tilt mechanisms. Possibly install new driver seat padding.

So I got 4 of the 5 things done. Finding a small case 410 LSD has proven to be a challenge. I'm putting my small case LSD search on hold in favor of having M42 resealed per what I said above.

[dugly52]

Super clean car. I like it!

To cut down on the coolant mess, I made a drain line from the block on my car. That way I can direct it where I want it to go, and not onto the sub frame to splatter everywhere.

Keep up the good work!

[M42Technik]

I recall seeing this car many times at Cars & Coffee, looks great. I'm near Tysons and come up to the show every so often, in my GC Impreza RS.

Lot of great detail work. I recall going through the same motions with my old 318iS.

Any complaints on the paint job Auto Quality Solutions did? Been looking for a good paint shop in my area that won't charge what D&V Autobody does...

Keep it up!