which head do i get?

[dumpydave]

Hi. I've just taken the head off of my 1986 325i and the reason my head gasket has gone is because the water ways have corroded away.I could get it welded but i went down to my local breakers and they have 2 heads down there for sale. One has 2.5 cast on it which i presume is the standard 325 head but the other one has 2.5/2.7 on it. What is this one off and would it be better to get this one. Will i have to change anything to put it on?Any help would be appreciated

[eltel]

hi..dont know the difference between the two but i recently changed my head from a 2.5 to a 2.5/2.7 and they were exactly the same fitment, gasket etc and runs fine on my 1988 325.

would be interested to know the reason for the extra 2.7 bit..though

[gooner1]

Got the 2.5/2.7 head on my 86 cab mate no probs with it in fact i asssumed it was the original one
as car has only done 94000 miles.

[kam-325i]

the head stamped 2.5/2.7 is for the 2.5 or 2.7 block, the head is the same for either engine.

What has you original head have stamped on it ?

The early 2.5 engines had a slightly higher Commpresion ratio.

[Templ8e30]

Have a look on the inlet manifold side of the head, above the inlet ports in the centre there is a 3 digit number cast onto it.

You need one with '885', a '731' or '200' will not work.

Cheers,

Iain T

[Speedtouch]

Why won't a 200 head work (these are for the eta engine IIRC)?

[Andyboy]

Why won't a 200 head work (these are for the eta engine IIRC)?

Because the combustion chambers don't have the machined away section to clear the 325i raised piston edge. Fit one and the engine won't even turn over.

The 2.5/2.7 bit is for when BMW ran out of old 200 (Eta) head castings mid 1988 and used the 325i '885' head for the last 325e's. These are called the 'Super Eta' and are mainly for the USA although some late European 325e's have them. Same shitty Eta cam, throttle body and ECU so no more power.
A 325e btw is the Eta version of the E30 - same engine, manual or auto gearbox and tall final drive from the 525e. They were a great car and do 40 mpg with ease on a run. Sadly they were never sold here.

[Speedtouch]

Cheers Andyboy, I see what you mean There's quite a good explanation here too

http://www.bmwe30.net/cgi-bin/datacgi/d ... Section=03

Sounds like the 'Super Eta' would have very low compression!

[dumpydave]

Have a look on the inlet manifold side of the head, above the inlet ports in the centre there is a 3 digit number cast onto it.

You need one with '885', a '731' or '200' will not work.

Cheers,

Iain T

Yeah checked this. The two heads both have the same casting number. I think this head (2.5/2.7) came off a 1988 525 which is obviously a later head than my 1986 325 head. The only noticeable difference i've seen is that the cam belt pulley is slightly thicker.Hopefully the ally is better quality as my old head just crumbled away. (running without anti-freeze i would imagine). This head has no corrosion what so ever, just shows the long term benefits of regular servicing.