Head gasket and parts change

[harold30]

Hi guys,

I decide to replace the head gasket due to high temperature on traffic. I have replaced clutch fan, fan blade, aux fan, water pump, termostat and so on. I experienced overheating before I replaced the parts but the issue still there. Can someone please enumerate the parts that needs to replace aside from HG while I'm there?

Thanks,
harold

[Sasquatch440]

hows your radiator look? a system flush wouldnt hurt

[harold30]

hows your radiator look? a system flush wouldnt hurt

radiator looks good and i flushed the all coolant after the water pump installed.

[e30davie]

Be very sure its the head gasket before you pull it off...have you done a cooling system pressure test? or a leak down test? Done a compression test?

Does the cooling system pressurize during operation?

[jlevie]

While a leaking head gasket could be the problem, a simple cooling system flush may not be sufficient. So eliminate that first buy performing a proper flush using a prepared flush compound. And consider taking the radiator out and having it checked professionally.

A DIY test for a leaking head gasket is to open the expansion tank cap on a cold engine, topping up the coolant if needed, drive the car until the engine is hot, but don't let it overheat, and let it sit overnight, Before you drive the car the hoses will be soft and easy to compress. If they are hard the next morning after driving you have a head gasket leak.

Simply changing just the head gasket has a low chance of success. Take the head to a shop and have it checked for flatness and cracks. Personally I have never seen a head come off an engine that didn't have at least .05" of warp, even when there wasn't a head gasket leak. So I alway have the shop take at least a minimal cut. I also have them check the valve guides for wear and grind the valves and seats. I always disassemble the head, marking each valve according to which cylinder is belongs to, to save machine shop costs (you will need a valve spring compressor). On I high mileage engine (over 100k) while the head is at the shop I'll check the rockers/eccentrics for wear or cracks and I'll check the cam for wear with a micrometer, and replace it or have it reground. The seals are easy to install as are the valves, springs, cam and rocker arm tubes (make sure the tubes are clean and the oil passages open & likewise for the spray bar). There are a number of folks that recommend lapping in the valves after grinding, but I've not found that to be necessary with the shop I use. But I'll agree that it is a good way to check the grind job

Use a BMW or Goetz head gasket and new BMW or VR head bolts. Chase the threads in the block and clean with solvent and compressed air. I normally only bring the head bolts up to the initial 22ftlb of torque before reinstalling all the the other bits and pieces, just in case the head has to come back off to fix something. That way I can reuse the the gasket and head bolts.

Don't forget to use new o-rings on the oil return tube. And of course you'll need new intake and exhaust gaskets as well as a new timing belt and tensioner. It the water pump & thermostat is of unknown age or over 100k, they should be replaced.

A head refresh after 100k will make a big difference in performance.

[ahlem]

Did you check to be sure the auxiliary fan operates correctly? There are several temp sensor ranges available. If you jumper the temp sensor at the connection to the radiator, you can determine if the two relays and the resistor are all operating properly. Did you actually measure the temperature or are you depending on the temp gauge?
There is a write up on here somewhere for the temp sensor jump process. It's cheap and pretty easy. Finally, did you heat cycle the car and bleed the air a couple times?

[jeffnhiscars]

I had cooling problems on my very 1st e30 and after multiple water pump, tstat and fan clutch changes I realized it didnt have a shroud :-)