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YOUR RESEARCHWhite, sweet vapor smoke from one side... Gasket or cracked head?
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Use on our m96 aluminum crank carriers
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As an example, look at the steel bearing cradle inserts used on our m96 aluminum crank carriers.
White, sweet vapor smoke from one side... Gasket or cracked head?
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Leading evidence: 'Use on our m96 aluminum crank carriers' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Run really nice' (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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White, sweet vapor smoke from one side... Gasket or cracked head?
Test must be done
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White, sweet vapor smoke from one side... Gasket or cracked head?
Test on bank 2
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Suggestion
You need to do a compression check and leak down test on Bank 2.
White, sweet vapor smoke from one side... Gasket or cracked head?
Use lower compression ratios, again a hp decrease
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Suggestion
To compensate for slower heat dissipation many manufactures that use steel cyl will use lower compression ratios, again a hp decrease.
White, sweet vapor smoke from one side... Gasket or cracked head?
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Hi...
I have a 2000 model 996 C4 coupe and am having an issue with cylinder 4-5-6 side of engine producing occasional white coolant vapor smoke (can tell from smell) that is somewhat intermittent and has been getting slowly worse.... The engine was rebuilt 10k miles ago and still runs fantastic. It's now a balanced & sleeved 3.5L with light tune and I guess it's pushing somewhere around 340-350 hp.... AOS has been swapped twice so far and it's still doing the same thing... I figure if the AOS was the issue I'd be getting smoke from both sides, not the the driver side exhaust.
So, I'm now shopping for right-side cylinder head to have on hand just-in-case the problem is indeed the head..., but thought I'd ask the brain-trust here if anyone has any ideas what could be causing this issue?
Any thoughts/ideas greatly appreciated.
It's never a head gasket. AOS problem would more likely result in sooty oily smoke on drivers side exhaust. You need to do a compression check and leak down test on Bank 2. Could be a head crack or cylinder D-chunck (cracked block). Good luck...are you loosing coolant?
DO NOT KEEP DRIVING IT, if coolant is intruding into cylinder/exhaust, you more than likely have (some) coolant washing into crankcase oil.
Antifreeze/coolant in oil will destroy your babbit engine bearings. Or you could hydro lock it.
A detailed coolant pressure test must be done.
Tow it to shop that rebuilt engine 10,000 miles ago
, as something is very wrong and they are the ones that put it together, hopefully with some type of warranty or good will. This should not be happening with only 10k miles after total rebuild...
This.
I'm moving back into
@jaetee
's area soon and am now VERY curious who did the work (if it was done in greater TPA area) ....and how this will play out.
My first rebuild, I did a steel sleeve. After 2k miles, I began to get white smoke and go through coolant. Tore it down and found a sleeve had slipped. Tough because it was running really nice.
This is what I've heard from engine builders. Steel and aluminum expand/contract at different rates, and sleeving an aluminum block with steel is not wise.
While that is true, it doesn't have to be, if builder understands what is needed.
As an example, look at the steel bearing cradle inserts used on our m96 aluminum crank carriers. Every bearing has a steel insert pressed in, and they never move that I've heard of. Trick is, proper engineering must be computed for the correct interference fit to keep things tight in all possible heat expansion possibilities the engine will experience.
Don't misunderstand me, I''m not pushing for steel sleeves at al, just that they can be done right and wrong. Although even if done correctly so they don't 'slip' out of position, they loose the much greater heat dissipation of aluminum cylinders. This will increase the threshold of detonation sensors reducing timing/fueling for a net decrease in HP/torque.
To compensate for slower heat dissipation many manufactures that use steel cyl will use lower compression ratios, again a hp decrease.
Might not be a lot, but its there and measurable and a decrease in hp.
jmo
This is correct. The liners are counter bored, installed with an oring against the bore, and the top of the liner has a protrusion spec (0.00x inch) which crushes against the head gasket for a positive seal. This is how it should be done if it is done.
Thanks for all of your input. The car runs like a freakin' dream and is considerably faster than it was before. Sucks to be dealing with this, but it is what it is... At this time the car is not being driven.
There is no intermix and only slight coolant loss. Once I have a replacement head on hand (just in case that is indeed the issue) the shop who rebuilt the engine will drop the motor and we will get answers. I know that things will only get worse if I keep driving it, and luckily I have other cars at my disposal.
This is a source reference. Confirm exact model applicability in the original material.
