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i'm on the road to full recovery now so back to the project car.......
So much milkshake in the coolant lines I decided to flush everything out with a hot mix only to find most of it on the sump.
Removed the AOS for checking and found a perished diaphragm upon cutting it apart could not fathom exactly how it worked though asI could not see any direct link between oil and water.
did a compression test and got the following numbers:
cylinder 1- 200psi
2-180
3-185
4-200
5-180
6-190
80psi Leak-down test showed the following
1-4%
2-6%
3-5%
4-12% air escaping from exhaust
5-14% air slowly escaping from inlet
6-4%
Decided to pull the engine and see what was going on inside.
Upon removing the RH head discovered the following:
One core plug was resting gracefully in the cradle of the camshafts having departed it's opening.
Not sure why this happens but it's not unique and race engines have threaded plugs.
The head appears to be sound and will be pressure tested.
The cylinders are as seen in the photos in the next post... there don't appear to be any obvious cracks but however there are 2 almost identical wiggly lines on the 'liner' ,they do not extend to the upper edge of the bore and there is no radial line extending to the outer edge of the liner.
I have seen these lines before on a boxster engine subject to a rebuild on the net, but they do not appear to be cracks............any ideas??
I will now pull the other head off to see what I find.
I will next crack test with dye the bores just to be sure.
Any thoughts would be welcome.... please take a look at the following pictures.......on the next post
Strange line same line different cylinder No. 5 Head core plug fail 5-6 head with gasket cleaned off cyl 6 RH cylinder head with gasket cleaned off no apparent leaks from Gasket as expected
The lines in the liners do not extend to the edge and the dark line at the edge/top of the piston is oil/solvent leaking after cleaning not a crack
Second head now off
Same lines but non reach the edge of the liner/bore
No apparent cracks in the head
So maybe it was just the core/freeze plug all along ?
I'm going to bet on the popped core plug being the root of the problem.. causing a hydrolock situation. with the leakdown #s maybe a few slightly bent valves as a result? good project you have going here.
That looks like a tiny bit of moisture pooled in the bottom. Can you feel a groove?
Hi Thanks for the input
That was my first thought as the engine was standing for several months to my knowledge.
It does look like a water mark and there is no detectable groove or crack so far...I'm sure the dye will tell me.
I can usually feel a couple of thou and theres nothing at all.
Last edited by trevorhp; 09-10-2018 at 08:24 AM.
Reason: added more answers
I'm going to bet on the popped core plug being the root of the problem.. causing a hydrolock situation. with the leakdown #s maybe a few slightly bent valves as a result? good project you have going here.
I think that's right. the core plug would have caused a mega intermix directly into the sump.
I cant detect any bent valves so far but removing them the lap the seats anyway so will find out soon.
Second head now off
Same lines but non reach the edge of the liner/bore
No apparent cracks in the head
So maybe it was just the core/freeze plug all along ?
I've seen the freeze plugs pop out of the heads before. It's a documented mode of failure and not unheard of. Like a previous poster said, these engines do not blow head gaskets.
With the amount of intermix, I presume you will take the engine completely apart to inspect the bottom end. We have pressure testing plates we use to pressure test the heads and case halves to ensure you don't have any other sources of intermix. We test at 40 psi.
The lines in the bores are normal visual aberrations in Alusil and Lokasil bores. I'd be more concerned with checking the bores for ovality and taper while apart and to make sure the piston skirt coating was not damaged on the pistons, as if it did get damaged, the bores will score shortly thereafter putting it back into service.
I've seen the freeze plugs pop out of the heads before. It's a documented mode of failure and not unheard of. Like a previous poster said, these engines do not blow head gaskets.
With the amount of intermix, I presume you will take the engine completely apart to inspect the bottom end. We have pressure testing plates we use to pressure test the heads and case halves to ensure you don't have any other sources of intermix. We test at 40 psi.
The lines in the bores are normal visual aberrations in Alusil and Lokasil bores. I'd be more concerned with checking the bores for ovality and taper while apart and to make sure the piston skirt coating was not damaged on the pistons, as if it did get damaged, the bores will score shortly thereafter putting it back into service.
Hi Charles, Thank you for taking the time to give me the detailed response, it is very welcome.
As I have no history on this car/engine I will tear the whole thing down to see where we are .
The bores do appear to be remarkably sound for 90k UK miles
Ovality is next on the list of checks.
Thanks once again
Trevor
Update
-ve
found 3 cracks in RH 4-6 Cylinder head probably the cause of the lost freeze/core plug.
+ve
Bores/liners not cracked the dye test appears ok
Purchased a sound cylinder head and a low temperature thermostat all for under 1500 USD
The original engine has double IMS fitted
So......
The rebuild begins Cylinders 5-6 after crack test Lines appear to be generic as Charles suggested 2 cracks allowing the freeze/core plug to fail Third crack in same head....steel core plugs alloy head ???? LH head all good so far
Quick update on this rebuild................
lapped the valves and found no bent ones so after replacing the stem seals they were all reinstalled
Took the opportunity to replace the core/freeze plugs with brass threaded plugs and the ends of the camshafts with similar brass plugs all Loctited in.
commenced the rebuild replacing all the gaskets and seals as I went along.
Bought a couple of pre=owned dansk boxes and fitted then after updating the flexible sections before they fail.
Engine back in now just a few hoses and lines to re-connect tomorrow then fill with fluids and crank over to build up pressures and flush the system.
Then drain everything, replace and try a startup
Wish me luck .......................
Pictures to follow
09-08-2018, 05:57 PM
