Alu M52 Overheating --- Update: Sill having issues

[Northern]

knock on wood that you won't need this, but if you ever do another aluminum block, just run the stock (aluminum block style, 10mm longer than the iron block style) headbolts.

The whole headbolt stripping issue seems to be people in NA using the iron block bolts. The euro guys seem to not have any issues (maybe they are just more familiar with the aluminum blocks because they're so common), and even run them to >500whp without issues.

[mjweimer]

3 1/2 weeks later, we have an update from the shop.
I imagine they opened it up and went, "oh, sheet."

As a reminder, this is an aluminum block. So the right thing to do is to Time-cert the block for the head bolts. They did.
But he says he found some of them loose. Somehow they backed out, reducing the clamping force. Hence, combustion could leak into the coolant.
This explains why the engine seemed fine in the beginning, before the head bolts were loose.
I certainly wouldn't have found this out easily. The only way was to take the head off.
He says the head and the block are still straight, so that's good.
To resolve the issue, he'll install new Time-certs the next size up, and put on a new head gasket.

I'm really bummed this happened the way it did. I feel bad for them, finding a problem like this. They're making it right, and I'm happy they're taking care of it.

I am glad to hear the issue has been found and they are working to resolve it. Kudos to the shop for standing behind their work. Hopefully you'll be back to enjoying the car sooner than later.

[Chilezen]

3 1/2 weeks later, we have an update from the shop.
I imagine they opened it up and went, "oh, sheet."

As a reminder, this is an aluminum block. So the right thing to do is to Time-cert the block for the head bolts. They did.
But he says he found some of them loose. Somehow they backed out, reducing the clamping force. Hence, combustion could leak into the coolant.
This explains why the engine seemed fine in the beginning, before the head bolts were loose.
I certainly wouldn't have found this out easily. The only way was to take the head off.
He says the head and the block are still straight, so that's good.
To resolve the issue, he'll install new Time-certs the next size up, and put on a new head gasket.

I'm really bummed this happened the way it did. I feel bad for them, finding a problem like this. They're making it right, and I'm happy they're taking care of it.

[Chilezen]

I'm counting on the stars to align and these events coincide! Hell, I hope it's done next week lol

[2mAn]

I mentioned my intention to drive up to the E30 Picnic at the end of June, and he said that's enough time to resolve the problem. Yeah, fingers crossed!

End of June?... I wonder how close I will be to completing my Twin Spark build by then haha

[Chilezen]

I received the engine as a long block, yes. Almost no accessories attached.

Within this past week, I didn't have time for that simple test for combustion gases.

I did drive the car 2 hours up to the shop on Saturday, so it's out of my hands/head. I had to add half a gallon of water 3 times. otherwise the drive was fine, I kept the temp under check. Compared to before, the new pump seems to have helped dampen the issue, so that's nice.

We'll see what happens! I also asked them to fix the inoperable Vanos. The shop was busy so it's not looking like a quick fix. I mentioned my intention to drive up to the E30 Picnic at the end of June, and he said that's enough time to resolve the problem. Yeah, fingers crossed!

[2mAn]

At this point I think it’s what you’ve feared all along and we’re hoping it wasn’t... but it’s related to the long block itself. Fingers crossed it’s a head gasket and that’s it. The leaking in the back makes me think that, did they deliver it to you as an assembled long block? Hopefully they will take some ownership of this when the problem is discovered

[reelizmpro]

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

It's not leaking past the threads. It's releasing through the cap itself. Look at the design of the cap, it's a pressure regulating cap which means it actually opens itself to relieve pressure and protect the cooling system. I've experienced this with my swap car.

[mjweimer]

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

I really hope you can get to the bottom of the issue...I imagine it has been frustrating. Let us know what you find out with the combustion gas testing.

[Chilezen]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure.

Given you have thoroughly checked all other components, I think performing this test would be worthwhile and the next logical step. I don't think it would be $$$ wasted at this point and will help set direction for the next steps.

Understood, I agree with your reasoning. Except for how, the cap should be draining it through the drain tube, which it does, but only the drain tube, and not past the threads of the cap as well. Anyway, yes, I'll rent a tester from the auto store.
Exhaust gases would probably explain the weird phenomenon of a hot/cold heater.

[reelizmpro]

Exhaust gas in the cooling system is also the reason why you can't bleed the system.

[mjweimer]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure. This is why I say, you need to test for exhaust gasses in the coolant. If the test fluid turns from Blue to Yellow at all you know you have a problem.

+1

Given you have thoroughly checked all other components, I think performing this test would be worthwhile and the next logical step. I don't think it would be $$$ wasted at this point and will help set direction for the next steps.

[reelizmpro]

My coolant cap didn't just leak, it expelled coolant like it was designed to do when the system is over pressurized. The cap is doing it's job by trying to maintain system pressure. This is why I say, you need to test for exhaust gasses in the coolant. If the test fluid turns from Blue to Yellow at all you know you have a problem.

[Chilezen]

"The coolant does still leak from the reservoir cap, and from underneath the rear of the head, as usual."

why you no fix this. its supposed to be sealed pressurised system.

Yes, I'm aware of this. I don't know why it leaks. I don't know how to fix it. I replaced both items, brand new. The new ones leak just like the other ones. There shouldn't be any secret to putting a cap on the reservoir and sealing the system. I feel like an idiot for missing something simple. If there's something that could help, I'd love to know!


--I haven't said this before but maybe this means something: I'll drive the car, stop, and I hear hissing from the cap. But I don't feel any fluid spraying out. When I slowly open the cap, I hear a new hissing, the exact sound of pressure being released from the system. So, there is pressure, and I can open the cap and the pressure releases. This is clear as day. But, I still see water marks inside the engine bay, coming from this area. Pictures from page 1:

The new reservoir looks like the old one: covered in coolant.

I don't know how fluid is getting out. I've tried a "normal" amount of tightening. A very tight cap. A loose cap. All same story. With two res's and caps.

You can use the e39 m52 thermostat housing which has a bleeder screw built into it. Makes bleeding a 24v much easier.

11531740478

I've seen this used. I will say I have vacuum bled the system, which was recommended by the shop I'm taking the car to. He always has success with it. I felt successful too when I did it. But yes, maybe that housing could help as well.

[bimr84]

You can use the e39 m52 thermostat housing which has a bleeder screw built into it. Makes bleeding a 24v much easier.

11531740478