Overheating and some other issues

[HappyE21]

I've just finished a fuel system overhaul (cleaned tanks and replaced all fuel hoses) and drove the car for the first time in a month. Since i got the car its had overheating issues but its been getting worse (never let it get over 3/4 and only driven it like 5 times) but that temp gauge will keep rising. It will get hot at idle with the hood closed, stays in the middle with the hood open, it really gets hot once you start driving. drove it today for 10-20 minutes and when i got back it was right at the 3/4 mark. I don't want to damage anything so i will fix this before I drive it again.

My other issue is that the exhaust pops at idle. note that there are 2 or 3 almond size holes in the muffler so maybe its just that. I've read it could be a vacuum leak or something with the valvetrain but i am not sure. I want to adjust mixture but not sure how to do that. I also have no clue how to check for vacuum leaks or how to do a valve adjustment, I'm still pretty new to cars so any tips are appreciated.

Thanks in advance
-Cole

[epmedia]

Does the cabin heater function properly?

Valve rocker adjustment is routine maintenance.

[HappyE21]

Does the cabin heater function properly?

Valve rocker adjustment is routine maintenance.

blower motor went out while I was flushing the block, ran distilled water through it 3 times, drove it with radiator cap off for like 20 minutes and temp gauge stayed in the middle.

[epmedia]

blower motor went out while I was flushing the block, ran distilled water through it 3 times, drove it with radiator cap off for like 20 minutes and temp gauge stayed in the middle.

I asked about the cabin heater incase the heater radiator may have been improperly bypassed, or if using the cabin heater would help to keep the engine cooler. Unfortunately the blower is not working to assist with tests. Alternatively (assuming the blower motor is stiff to turn) - you can access the blower motor's carbon brush set and bearings(bushings) and give then a blast of wd-40(a solvent) to help free the blower motor to spin freely. Or is the blower motor fuse the culprit?

Link to the 1980 320i Electric Manual (ETM)

I'm assuming since your heater blower was in use while flushing, that you are aware that the heater must be on full hot when bleeding the cooling system.

Since it runs cooler with the rad cap removed, I have a suggestion to check for air bubbles/combustion gasses in the engine's cooling system... Do not put your face over the funnel when testing - While the coolant is at safe temperature/pressure - Use a hose that fits snug into the radiator fill hole and snugly insert a large funnel to the other end of the hose. Add some distilled water to the funnel and monitor for bubbles that come up while at idle and while blipping the throttle (hard and quick throttle blips to pressurize the combustion chambers whilst not increasing the engine rpms). Do this while the coolant is relatively cool (safe temp) and while the coolant is warming up and while the thermostat begins to open. More bubbles while blipping the throttle indicates possible head/gasket failure - if big bubbles it's probable head/gasket failure. Cavitation on the water pump can also cause bubbles, thus why we try not to increase the engine rpms while doing this test. If you prefer - there's also test kits for combustion gasses in the cooling system.

You can also test or replace the thermostat as well, especially if is old and possibly crusty. Original is 80c (176f) - straight up on the temp gauge. When 5/8 -3/4 on the gauge (depending on temp rating of the switch), the aux cooling fan should turn on.

Possibly the radiator is dirty, even after flushing. Is it an all-metal radiator, or does the radiator have plastic tanks?

[HappyE21]

Turned out the fuse for the blower motor melted, all fixed. I drove the car for like 20 minutes with rad cap off and the temp did stay right around the middle so I'm not too worried about it right now. I replaced the thermostat and everything seems to be flowing through the radiator properly. I rinsed the radiator out with the garden hose until the water came out clear. I'll probably go a little over the top with the cooling system in the future once i get everything else sorted out but i think that its alright for now.

I put my hand over the holes on the muffler and the popping stopped so I guess ill just buy a new muffler, maybe I'll get one of those fancy ANSA 2 tip ones

I do want to get this car running nice before I start tearing into all the rust that's on it, but more stuff just keeps popping up every time I drive it.

I think that the headgasket is okay, ill be doing a compression test soon. But the guy that I bought the car from got a new headgasket in 94' around 70k miles ago.

[cgifool]

For next time, there's a coolant drain plug on the side of the block, under the exhaust manifold. Remove it and blast water in that hole as well as part of a flush. Put a new seal ring on it when you reinstall.

[HappyE21]

For next time, there's a coolant drain plug on the side of the block, under the exhaust manifold. Remove it and blast water in that hole as well as part of a flush. Put a new seal ring on it when you reinstall.

Got it. I knew there was a drain plug somewhere, just couldn't put my finger on it.