8 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHWhere in the heads are the cracks?
Leading reported evidence
Use gasoline
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Performed · outcome unconfirmed
Yelcab, you clean the cam side of the head as best you can, I used gasoline with a round paint brush to get in all the crevices/corners then blew it out with compressed air.
Leading evidence: 'Use gasoline' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check with dye' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
Fairly simple process, but you need to be particular about cleaning between steps to avoid false readings.
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Suggestion
I used a penetrant dye test kit consisting of a cleaning spray can, a red dye spray can, and a white developer spray can, cost about $15 if memory serves.
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Performed · outcome unconfirmed
Yelcab, you clean the cam side of the head as best you can, I used gasoline with a round paint brush to get in all the crevices/corners then blew it out with compressed air.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
I used a penetrant dye test kit consisting of a cleaning spray can, a red dye spray can, and a white developer spray can, cost about $15 if memory serves.
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8 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T035758Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I'm stripping down a 3.4L 996 engine with some symptoms of cracked heads. So far, compression is good, leak down is good, spark plugs look good, no intermix in coolant or oil. The only symptoms are loss of coolant and white smoke coming from the back of the car. I am unsure (Because it has never happened while i am there) if the smoke is coming out the tail pipe or coming out around the back of the engine (coolant on hot exhaust).
I have stripped down the engine to the heads, cam shafts removed (head still on the block). I have not seen any cracks from sparkplug hole to valves. Where are the other potential crack areas? I don't have a problem of removing the head and looking at the chamber.... if that is necessary.
Pressure check with dye.. there are a couple places mentioned on here that specialize in these heads.
Like a lot of things on the 996,, its too top heavy to set up to do one set.. IMHO..
But any stories you end up with please post then we all learn ...
I used a penetrant dye test kit consisting of a cleaning spray can, a red dye spray can, and a white developer spray can, cost about $15 if memory serves. Indeed, a nice large crack appeared between a spark plug hole and a valve stem. Valve stem to water jacket plug is another area susceptible to cracking. Len Hoffman in Georgia (Hoffman Automotive Machine) is the acknowledged expert in these repairs, he did right by me and at a very reasonable price. Best of luck.
These are all 3.4 heads and are all the inner exhaust spring seat on cylinder #1 with cracks running from the spring seat to the sparkplug chase. The last one is from my car in 2008 and the others are different heads that I have worked with the owners on. I believe that crack in this area are one of the most common but there are cracks in other areas too. I have more pictures of such cracks but I thought this would be enough!
Yelcab, you clean the cam side of the head as best you can, I used gasoline with a round paint brush to get in all the crevices/corners then blew it out with compressed air. Then you spray down the cam side of the head with the cleaner spray can, stand the head up on one end so that all the spray cleaner drains out the bottom. Wipe it clean with lintless rags and let dry. Now spray the cam side of the head, concentrating mostly on the floor, with the red dye spray can till you've got a nice even translucent red coating. Now take some lintless rags and moisten them with the cleaner spray can and wipe out as much of the red dye as you can possibly remove. Repea this step till its all pretty much gone. Now spray down the cam side of the head, concentrating mostly on the floor, with the white developer spray can until you've got a uniform white coat on the floor of the cam side of the head. If there are any cracks they will now appear as fine red lines through the white developer. Fairly simple process, but you need to be particular about cleaning between steps to avoid false readings. Sometimes the cracks are so pronounced that you can see them without the dye penetrant test. Mine were finer so needed the penetrant test, but thankfully limited to the one spark plug hole.
Alright, I think this is the next to last report.
No intermix of fluids (huge relief)
Good even compression all across
Good and low 3-7% leak down on cold engine, on all cylinders
Visually inspect all heads top side. No cracks are found on heads.
What I did find:
Bad AOS via smoke test
Leaking pressure relief valve on coolant tank (coolant tank is OK).
Those issues have been addressed and engine is almost ready to go back in after a bunch of other things also addressed.
This is a source reference. Confirm exact model applicability in the original material.
