Blown Head Gasket?

[S Lawns]

I have had my 1992 325i in the shop a couple times for overheating issues and the shop suggested that the head gasket may be bad. Has anyone ever replaced themselves and how big of a job is it?

[winfred]

the unfortunate fact is if it still runs good the head may be cracked, generally when the gasket blows it goes big and effects the running, before you tear it apart check the pisser line from the right side (as you are looking at it) of the radiator for free flowing coolant into the bottle as you rev it with the cap off, no squirt into the bottle it's, A, low on coolant, B, clogged, C, no coolant flow due to stuck closed thermostat or busted plastic impeller water pump (these will make it overheat fast) plastic water pumps are getting rare but they still show up occasionally, the best test i've found for a cracked head requires a air compressor and a compression tester with the air coupler type connection so you can hook it to a air hose, remove the schrader valve from the compression tester so you can blow though it, fill the cooling system to the top and start pressurizing the cylinders, you will need to roll the engine over and hold it when you feel/hear it holding the pressure when both valves are closed, watch for the coolant rising, if you do all 6 and get no burp the gasket/head is most likely fine

quick tip to make filling the cooling system easier is to drill a small hole where the arrow is on the thermostat before you install it and put it straight up at the 12:00 position, around 1/8" will do

[S Lawns]

Thanks winfred. I will try some of you tips but let me know if my events below give you any other thoughts.

Late in May I had just headed up the road about 10 miles and the water pump broke and the belts were thrown off. I towed it to a friends shop and had them replace the water pump and belts. I picked it up on Tuesday and drove it around town a couple days and I noticed it was leaking. On Friday that week it overheated on the freeway after just a few miles. I saw it was blowing out from the radiator cap and so I filled with cool water and drove straight back to the shop.

The said the fan clutch was bad and so they replaced it, the thermostat and housing along with a new radiator cap. Picked it up again and drove it a couple days and it started blowing out the hose where it was connected to the thermostat housing. I could see the clamp had cut the hose. So I took it back again and they replaced the hose.

Now when I started it, it ran really rough for a minute or two. Seemed like it was down a couple cylinders. Drove it a mile or two home and smoothed out but it was already at the red light on the temp gauge. No leaking anywhere though.

I let it cool completely and then started it again and it was really rough so I pulled it in the garage and there it sits for the last couple weeks.

[Ferret]

Now when I started it, it ran really rough for a minute or two. Seemed like it was down a couple cylinders. Drove it a mile or two home and smoothed out but it was already at the red light on the temp gauge. No leaking anywhere though.

I let it cool completely and then started it again and it was really rough so I pulled it in the garage and there it sits for the last couple weeks.

Rough starting usually means there's water in the cylenders - usually a cracked head.

Best way to tell is leave it overnight, pull all the spark plugs and kick it over on the starter. If you've got water in the bores, you'll know about it...

Brings back memories of M50 diagnosis and 10 ft arcs of water out of the block :D

EDIT : having seen it's a '92 and an M50 - I've been through pretty much your exact symptoms with a '92 525i M50. It started as a simple bad head gasket, but because it was driven further and overheated 2 or 3 times the head cracked between cyls 2 and 3 - then went on to do the bad start thing just like you're describing.