D15, D16, D17 and Mini-Me swaps
By SL93ex
#305161 Roughly a month ago, I replaced the head gasket on my z6 because it overheated and started eating a little coolant.
I had the head milled and I replaced seals and what-not.
I used an MLS head gasket and ARP studs.
Once it was all back together, it ran great.
I have re-checked the torque on the studs.

Early this week I dropped my kid off and started the car and it barfed out a cloud of white smoke and ran like shit. When I popped the hood I noticed it was a 1/4 full in the coolant tank. I've been watching fluids so I know it was good the day before.

After having it towed to my house, I started it to reposition it as it came off the wrecker and It started and ran fine, no smoke. Today I started it and took it for a short drive, and it was all good.

I'm assuming at the very least the head gasket went again, but could it be anything else? Should I pull the block and have it decked? Money is definately an issue, but if I pull the motor I'll have to rebuild the bottom end (I'd have to right? Could you tear a motor down and not rebuild it?)

I have considered sourcing a d15/+ecu or another z6 but people around here want stupid amounts of money for barely running engines.

I kinda know what I have to do, but I'm hoping someone can pat me on the head and tell me it'll all be okay because it's something else cheap and easy.
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By teal_dx
#305162 It sounds like you did everything correctly.
Is the motor stock? How many Miles? First thing to figure out is why is it getting hot to begin with. Fan is working ok?

You could tear the motor down and not have to rebuild if you record the position of each bearing, rod/piston so that it goes back together the exact same way as you tool it apart.
By SL93ex
#305173 The motor is mostly stock. IHE plus the head milling. 160k miles. Stock tune.

The first time it started to overheat it was the fan.. It was in the winter and I caught it before it became a problem. (Not much over halfway on the temp guage). This was fixed with a new thermoswitch and a manual switch on the dash.

The second time was more serious.. a heater hose ruptured and I lost almost all the coolant. I limped it home, stopping from time to time to let it cool down. It was after this that it started losing coolant. Not much, but it was enough to convince me to replace the HG.

After the HG change I haven't had ANY problems with overheating or lost coolant until early this week when it started blasting out white smoke.

Is it possible that the overheating caused the block surface to warp?
It's entirely possible that I didn't clean the surface of the block good enough... I'm not above that kind of mess up :oops:
The machine shop said the head was fine after they cleaned it up and resurfaced it. Could it be cracked? The intake manifold?

I thought about careful reassembly with old bearings and rings, but at 160k miles I just couldn't bring myself to do all that work without replacing them with new stuff.
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By teal_dx
#305222 The second time sounds like it could have done some damage. It's usually the head that warps, not the block though.

Next time clean the surface really well and use some copper spray on the headgasket. Also check for any nicks or deep scratches in the surface which could be a path for leaks.

Yeah, at 160k, you might as well rebuild :thumb:
User avatar
By d-mon
#305236
SL93ex wrote:It's entirely possible that I didn't clean the surface of the block good enough.

most likley, this.
if you wouldn't eat off of it, its not clean enough.
i have replaced headgaskets many times, and done many more head swaps.
for years i used (and reused) ebay head gaskets with no problems, but one time after a few weeks it blew so now i only use new Honda headgaskets from the dealer. $46
copper spray is for composite h/gs, not mls.
By SL93ex
#312161 Well it's been 3 weeks since I went ahead and changed the head gasket again...

I took d-mon's advice and attacked my block with fine steel wool (after taping the cylinder and plugging the holes)
I literally wore my fingers out but I got it to the point where I would eat off it :hehe:

So far so good...

I also installed a full EK console, but that's for another thread.
By EJ1_MK
#312193 Did you use a honda head gasket? I have heard that aftermarket one tend to pop much easier than factory. Even on stock motors.
By SL93ex
#312210 The first one was from Honda. I don't remember the brand, but I got it from the dealership. The new one, I'm sad to say is a Fel-Pro MLS. I've always had great luck with Fel-Pro with muscle cars, so hopefully the luck will carry over.
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By sensei
#312241 sounds like the motor was pretty seriously overheated. Next time take a straight-edge to the deck to see if the block warped.