Massnz

Obligatory update (its a pain in the arse when you read threads while diagnosing only to get to the last page and have no update from the OP), got myself a new expansion cap and gave the system another good bleeding. Warmed it up to temperature and took it for a good hard drive the same route I normally do and the hoses didn't feel as hard as usual so i'll let it cool down and see how it is. The new cap seemed to spin a lot more freely and had more play in it than my old cap which would jam up if you twisted the stalk around, so maybe the cap was sticking and not allowing the system to adequately vent into the overflow. I always thought the failure mode on a rad cap was excessive venting due to a failure in the spring mechanism which is why I overlooked this item.

Nice. Same as my 328 just with different wheels and the kit.

Follow your nose. Could either be fuel filler cap, injector o-rings or leaking fuel hoses. You COULD try spraying a small amount of carb cleaner at each of the injectors using the plastic tube nozzle and on a cold engine to see if theres a change in idle speed. Try keep it away from your exhaust manifold. That metal plate under the rear seat will be your fuel pump and possibly your secondary fuel level sender unit if there's another plate on the other side.

The issue I'm having is the cooling system is staying pressurized after cooling down. Ends up barfing a couple hundred ml of coolant out when I pull the expansion cap. I'm about to change the cap and check the thermostat, but thinking I may have a small leak at the heater core allowing a bit of air into the system. I still have that thought in the back of my mind that there's a head gasket breach that won't show up on a comp or block test.

I've been throwing in the cheap Warehouse pre-mix stuff while I work on the car, once everything's sweet then i'll flush and put in some better stuff.

I was getting mine up to temperature the other day with the cap off while bleeding and it did the same thing. Some very large bubbles came from the bottom of the reservoir (a bit like the bubbles you get at the hot mud pools). I've performed a few teekay block tests and detected no exhaust gasses and compression is 179 - 181 across the board.

By the way I'm in a similar boat with my cooling system at the tail end of my build. M52b28 here.

Pretty sure that's normal? If it is at operating temperature and you have the expansion cap off the system isn't retaining pressure so the coolant is effectively boiling.

I have the Vanos Adjustment Wrench and the Alignment Set (didn't come with the crank locking pin but i managed without). I tried using a set of Slip Jaws for the rotation of the exhaust sprocket but failed miserably and bit the bullet.

Maybe try dropping the oil, and run a strong magnet through it to see if there's any metal shavings? You can get those neodymium magnets for doors from Mitre 10 for like $10. If you hadn't have gotten it checked over by a Euro Specialist I would have been looking more towards either Vanos, a coil pack, crank or cam sensors.

Funny I spent half commute home reading up on rad cap symptoms. Short answer is no so I'll give that a go. I assume the cap is designed to allow coolant to flow from the overflow pipe into the expansion tank once the system reaches operating pressure, so if it's stuck then pressure builds up in the rad and has no where to go particularly when the system cools down... until I open the cap?

What did it set you back in the end?

Yeah that's what I was thinking but after performing several teekay tests for combustion gases and having them come up all good I'm not sure. Performed the tests from cold to hot and gave it several blasts of the throttle but the fluid stayed blue. I'm not having any coolant push out past the rad cap while the car is running which makes me wonder if I'm just being paranoid.

Still having some issues. Fully bleed the system after i put in a new waterpump (cars been sitting around for a while), took it for a good blast yesterday afternoon with the heaters blowing hot and parked it up for the day. Checked the cooling hoses 26 hours later and they were hard (just a little less than operating rigidity), cracked the rad cap open and a couple hundred mls of coolant came gushing out. Reservoir level is still sitting at the cold line. I performed a few tk tests over the weekend which appeared to come up all good and a compression test a month ago came up 180 on all 6 cylinders so a bit confused. Am I just being overly paranoid?

Hello 1996 E36 M52B28....I fully bled my cooling system by jacking the front end up about 500mm and it seemed to be successful. Hot Air coming from the heater and no visual coolant loss or overheating. Drove the car about 30kms to drop it off at the Car Transporter as we were moving Islands, everything seemed to be all good. 5 days later I go to collect my car from the drop off point, open the radiator cap to check the coolant level prior to driving and there was a very loud pop/boom like opening a Corked Wine Bottle but with a much deeper tone. No coolant splashed out so i assume this was under vacuum? I then drove it home (6kms) and parked it up. Next morning (12 hours later) the hoses still felt a little rigid (about halfway between when the car is running and cold with the cap off). Opened the cap and it made an audible sucking/gurgling noise with a little bit of coolant streaming out from the small upper radiator hose into the expansion tank. Is this likely to be due to an Air Pocket being present in the system creating a vacuum or could I potentially looking at something a little more serious?