signs of a blown head gasket

[cprince]

What are the signs of a blown head gasket on an E30? Thanks.

[moberg12]

Coolant in the oil, Oil in the coolant, thick white smoke coming from the exhaust. You might have one of the symptoms or you might have all three

[thejlevie]

For the sake of completeness, the possible list of symptoms of a failed head gasket are:

Coolant leaking into the crankcase (milky emulsion in the oil)
Coolant leaking into a cylinder (white smoke from the exhaust)
Coolant leaking from the head seam
Oil leaking into the cooling system
Oil leaking into a cylinder
Oil leaking from the head seam
A leak from a cylinder to the cooling system
A leak from a cylinder to an oil return passage
A leak between cylinders

Of those the most common are a leak between the cooling system and a cylinder (withe smoke or overheating) and a leak of coolant into the oil (milky emulsion in the oil).

[ganzibye]

yah..all they said are right

[PRoland]

All of the above.
Mine showed three or four of those symptoms.

Remember - when the engine is running some of these things occur, when the engine is off, others may occur.
For instance:
1) At startup, I got white smoke out the tailpipe because last time the engine was shut, the coolant was still under pressure. Highest coolant temp/pressure is often just *after* engine is shut off, allowing coolant to collect inside the cylinder.
2) After startup, exhaust gases can press into the coolant causing foaming, which will cause coolant to push out the overflow tube. This will dissipate if the car has been sitting and coolant level will eventually appear low.
3) I also had oil push into the coolant, which makes for a chocolate mousse. Not always terminal unless engine overheats.
4) Plus I had an external leak down the right rear of the block.

Figured it was about time to do the gasket. :o)

My 325e had about 245k on it at the time (last year). Running great after.

[T77911S]

those are if it is bad.

hi pressure in the cooling system. coolant blows out after turning the car off, it takes a while. it may run rough when first starting cold. you may smell coolant, it would be coming from the exhaust.

i drove my volvo 960 with a bad HG for about 2 years. i always suspected the HG. i tested the HC's in the colling system, many times, ran compression/leadown tests, they all appeard good, but i would randomly lose coolant. the cooling system hoses would be rock hard about 10 minutes after turning the car off, i found all the weak spots in the cooling system. finally the cold stating started to get worse. it would run on 5 cylinders until the bad one would clear up and fire. so, chck the rpessure in the cooling sys or at least keep an eye on it

[cprince]

thanks for the replies! The only real indication that I have is I saw some oil film in the coolant reservoir. The car is an '87 325e with 225k miles on it. I'm going to change the timing belt on it, so I figure it might be time to change the head gasket too. What do you think?

[thejlevie]

Flush the cooling system with any of the commercial flush products (procedure below). Then see if oil again shows up in the coolant. Note that on a car with an automatic transmission a leaking transmission cooler (in the radiator) will result in oil in the coolant.

Use of one of the commercial cooling system flush products will do a more
through job of cleaning the cooling system than simply flushing with
water. The process I use is:

1) Drain the old coolant and remove the thermostat. When the thermostat
housing seals with an o-ring I make up a gasket out of pasteboard for a
temporary seal. With the thermostat out you'll have full flow through the
system the entire time the engine is running. Filling an bleeding will be very
quick and easy since the thermostat won't be blocking airflow out of the
block.

2) Add the flush compound and fill the system with water. Bleed per normal
procedure so that you don't have an air bubble in the block. The higher you
have the front of the car (with the rear wheels on the ground) the easier it
is to get to the block drain and the easier it will be to bleed the system. I
like to have the front at least two feet higher than the rears.

3) Run the engine and get it to normal or near normal temperature. In cooler
weather this will require blocking some of the airflow into the
radiator. Generally you need for the engine to be at temperature for at least
15 minutes for the flush compound to do its work. The heater needs to be on
and you want to be sure to not allow the engine to overheat.

4) Shut down and allow the engine to cool to the point that you can keep your
hand on the thermostat housing and cylinder head.

5) Leave the expansion tank cap on and open the block drain. Only a small
amount of liquid will be released because the top of the system is still
sealed. When you loosen the cap the rest will flow out. Doing it this was
reduces the chance of a scald. Once the block is drained put the plug back in
finger tight and drain the radiator. Close the radiator drain when the fluid
is out.

6) Fill the system with hot water and bleed. Then run the engine long enough
to get it up to temperature. That's probably 10-15 minutes. Using hot water
reduces the time required to reach operating temperature and keeps from
having to idle a cold engine over and over.

7) Allow the engine to cool (as in 4 above). Then drain the block and
radiator, catching the fluid so you can see what's coming out of the cooling
system.

8) Repeat the fill & drain sequence until the water coming out is
clear. Depending on how dirty the cooling system was it may take 8-10 cycles to
get to clear water.

9) Re-install the thermostat, properly tighten the drains, fill with coolant,
and bleed the system.

[RangerGress]

If the only symptom is some tiny bit of oil in the overflow reservior, I'd let it go.

[ngcreese]

+1 you guys are right on point ob the symptoms.

Might add... pay close attention to the sides of you engine block for any signs of oil / coolant leakage from the head gasket.