Jump to content

Cracked E12 Head? Swap to my spare 121...?


Recommended Posts

'73 tii

I think my head is cracked. I had my exhaust manifold off to investigate and oil ran out of cyl. 2,3,4 when I first cranked it, smoked, and cleared up. This leads me to suspect oil leaked down since the last time I ran it, was forced out when I cranked and then burnt out. My vave train is coked pretty heavily and smelt strongly like combustion gasses when I took the cover off. I continued to remove the head. Head bolts were quite sludgy and wreaked of burnt oil. I inspected the head gasket and combustion chamber, and besides light scoring on on cyl. 1 (the only one not losing oil), no defects noted. No coolant or oil contamination. No compression test was performed before dissasembly.

I parted out a '72 2002 and have its engine components. It never ran nor did I attempt to get it going so it's mechanical condition was entirely unknown. I tore into it to compare it's condition and it was very clean up top, reinforcing my suspicion of combustion gasses getting up and oil getting down. With just a rough visual inspection, it seems alright.

Assuming my bottom end is sound, it seems to me that I have 2 options:

1. Top overhaul. Have head tested for cracks/ flattness. Replace valve stem seals/ valve guids. 

2. Swap for spare. I read that the 121 head was superseeded by the E12 so can I go backwards? Not my no. 1 priority but how much of an effect would this have on my car.

I have lots of pictures but not sure what to include.

I was ready to start firing the parts cannon but I'm trying to think through the puzzle first. Any of your thoughts are welcome.

Cheers,

Summit

Link to comment
Share on other sites

What you don't say:

 

Are there any cracks in the E12 chambers?

They will be obvious to a careful visual inspection.

 

Oil almost NEVER leaks due to a crack- 99 44/100 % of all cracks let combustion gasses

out of the chamber, or water into somewhere it shouldn't be.

Oil is often valve stem seals, as the valve guides on an M10 take a lot of side loading,

and thus, wear pretty quickly.  M10s also tend to not do much mileage compared

to age, so the stem seals get hard, and then let lots of oil by them and into 

the ports.

 

So yes- get your head examined!  Both for cracks and for warping.

 

And then fix your fuel system, and change your oil more often.

Coking with modern oils is indicative of too long a change interval (on an M10)

and reeking of fuel is an overfuelling situation.

(which will then wreak havoc on the oil's lubrication properties)

 

Yes, the 121 head won't fit over tii pistons.   Unless they're 121 tii pistons, which are

different to E12 tii pistons.

 

t

has a lotta cracked heads in the attic 

 

Link to comment
Share on other sites

17 minutes ago, TobyB said:

What you don't say:

 

Are there any cracks in the E12 chambers?

They will be obvious to a careful visual inspection.

 

Oil almost NEVER leaks due to a crack- 99 44/100 % of all cracks let combustion gasses

out of the chamber, or water into somewhere it shouldn't be.

Oil is often valve stem seals, as the valve guides on an M10 take a lot of side loading,

and thus, wear pretty quickly.  M10s also tend to not do much mileage compared

to age, so the stem seals get hard, and then let lots of oil by them and into 

the ports.

 

So yes- get your head examined!  Both for cracks and for warping.

 

And then fix your fuel system, and change your oil more often.

Coking with modern oils is indicative of too long a change interval (on an M10)

and reeking of fuel is an overfuelling situation.

(which will then wreak havoc on the oil's lubrication properties)

 

Yes, the 121 head won't fit over tii pistons.   Unless they're 121 tii pistons, which are

different to E12 tii pistons.

 

t

has a lotta cracked heads in the attic 

 

I changed the oil when I got it but it hasn't been driven or registered in 25+ years. I got it from a friend who had it garaged for 20 years and I have been restoring it for the last 4. It has about 60k on it which is when I saw that the seals tend to go out. As for fuel I rebuilt the fuel injection pump, electric pump, and put a new belt. I really have been trying with the fuel and think its alright now. I've only been around the block with it so I couldn't really tell you about performance issues but my spark plugs and contacts were wide open so it could've been weak spark and incomplete combustion.

Link to comment
Share on other sites

If you do end up refurbishing your current E12 head, or acquire another one, do have the shop install the later style guides and valve stem seals from the M10 engine used in the E30s.  A very much improved design that will last a lot longer than the original '02 era design.

 

mike

Link to comment
Share on other sites

3 hours ago, NickVyse said:

If you pulled the upper the studs for the exhaust maifold then they're drilled through to the inside of the head and will have leaked oil, leading you to beleive it was actually coming from the ports.

IMG_1178.HEIC

Ah very interesting I hadn't realised that before. You can see a seam of oil coming out of this stud I pulled. I dont think this is what I observed however. I pulled the manifold off origionally to investigate oil leaking past the gaskets, and running down the side of the engine. Judging by the sheer amount of oil and the fact that it was an issue before the studs came out I doubt this was the root cause.

Link to comment
Share on other sites

3 hours ago, 2002iii said:

Sounds like it came out the exhaust ports.

Yes right out the exhaust ports. Heavy stream at first then seemed to clear up. I should've clarified. I had a puddle on my creeper which happened to be right under after just a few seconds😅

Link to comment
Share on other sites

5 hours ago, NickVyse said:

If you pulled the upper the studs for the exhaust maifold then they're drilled through to the inside of the head and will have leaked oil, leading you to beleive it was actually coming from the ports.

Hence my question about the source. Those studs need to bfe installed with sealant.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share


  • Upcoming Events

×
×
  • Create New...