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Discussion Starter #1
Key engine info:
OBDI H23a1 – built bottom end and stock head; approximately 20,000 miles on both
550cc injectors, AEM fuel rail and AFPR, 255lph walbro
Hondata s200
ARP head studs

This engine ran with a turbo for about 15,000 miles before going back NA to diagnose an oil burning problem.

I removed the head from the engine to have the valve guides replaced; engine burned oil on cold startup and under high vacuum….I replaced the seals first but that did not solve the problem so it must have been the guides. I had a spare cylinder head that I had the head work done on to limit the amount of down time. After inspection, it was found that the exhaust guides on this head needed to be replaced. I had the guides replaced, complete valve job, new seals, pressure tested for cracks, light mill pass to make sure it was flat.

Before installing serviced head I made sure the block deck was clean and flat using a precision straight edge and feeler gauge. I used new OEM head gasket and dowel pins. Installed head and torqued ARP nuts to 80ft.lbs in three steps using ARP assembly lube. At this point I did a leakdown test to make sure all cylinders were sealing properly and they were. Put the engine back together and made sure valve lash was set properly.

The current problem after driving ~200 miles:
40% leakdown on cylinder #2
70% leakdown on cylinder #4
<10% leadown on cylinder #1 and #3

All leakdown appears to be coming from exhaust valves as I can feel the air rushing from these ports. There also seems to be coolant in the oil. The coolant in the oil makes me suspect bad head gasket. After having a valve job how can these valves not be seating right? Again, I made sure the valve lash was set properly so I don’t think they were burned that way. I don’t think the car is running lean because it was running just fine before this other than the oil burn problem. Are the valve problem and coolant/oil mix problem related? Let me know what you guys think.
 

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The only way to diagnose valve problems are either time consuming or expensive. The cheapest solution is to buy a used low-mileage head, clean it up a little, and bolt it on. I think it would be worth it just to re-test for leakdown and prove your current head is the problem. H23 heads are very cheap. I once sold one for $25. :p
 

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Discussion Starter #4
Thanks for the advice. Anyone know if a leaky head gasket can cause elevated combustion chamber temps?
 

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just check your valve lash. If you got new valves or a valve job, they may have not set the valve lash properly.
 

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Discussion Starter #6
As stated twice in the original thread, the valve lash was checked and has been checked and is correct.
 
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