What happened to my engine???
Thread Starter
Racer
Joined: Jun 2009
Posts: 409
Likes: 3
From: St. James, NC
What happened to my engine???
I drove my 71 LS5 to Northern KY this afternoon …60 miles round-trip, about 50 of it highway. Engine ran rather warm on highway 220 to 225, but cooled back down to around 195 to 200 on secondary roads. Later that evening jumped into the vette and drove to cruise-in, stopping at BP on the way. I usually splash a little octane booster in the tank at each fueling, but didn’t have any so only put in 4 gallons of 93. At the cruise-in the engine ran-on when I shut-down. I let out the clutch to the stop run-on figuring the cause was the lack of octane booster (though to myself crappy gas). After about 90 minutes went to leave and the car hardly wanted to start, and won’t idle without help from the accelerater. Noticeable reduction in power and every time I shifted a great big puff of white smoke out the exhaust. It ran great before I departed the cruise-in…I didn’t beat on it or anything, just a nice afternoon drive. What’s wrong with the engine? What any I going to have to do the fix this?
Le Mans Master
Joined: Oct 2000
Posts: 6,362
Likes: 30
From: Oak Harbor WA
White smoke can be an indication of water (coolant) in the combustion chamber, if the engine is warm that is, otherwise on a cold engine it is likely just condensation in the exhaust burning off. 225* isn't really really hot but it can be the limit for an older car like yours. Also keep in mind your temp guage may not be completely accurate any longer. Pull and inspect the plugs real good, do a compression and leak down test as maybe you did some damage.
Intermediate
Joined: Jul 2010
Posts: 44
Likes: 0
Cracked head/head gasket worst case scenario.
The loss of power is more worrisome to me than the smoke.
Check your coolant for oil and your oil for coolant. Also the levels of both. Then maybe look at plugs to narrow it down.
Maybe someone else has an idea that doesn't involve such bad news.
The loss of power is more worrisome to me than the smoke.
Check your coolant for oil and your oil for coolant. Also the levels of both. Then maybe look at plugs to narrow it down.
Maybe someone else has an idea that doesn't involve such bad news.
Thread Starter
Racer
Joined: Jun 2009
Posts: 409
Likes: 3
From: St. James, NC
Cracked head/head gasket worst case scenario.
The loss of power is more worrisome to me than the smoke.
Check your coolant for oil and your oil for coolant. Also the levels of both. Then maybe look at plugs to narrow it down.
Maybe someone else has an idea that doesn't involve such bad news.
The loss of power is more worrisome to me than the smoke.
Check your coolant for oil and your oil for coolant. Also the levels of both. Then maybe look at plugs to narrow it down.
Maybe someone else has an idea that doesn't involve such bad news.
So the heads will have to come off at a minimum??
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
I would say that dieseling and stopping it suddenly/mechanically with the clutch put a lot of strain on the timing chain and gear. It may have jumped a tooth or two, particularly if there was some stretch already present in the chain. Using a timing gun is inexpensive and will say aye or nay to this possible problem.
Intermediate
Joined: Jun 2006
Posts: 47
Likes: 0
Dieseling could be caused by running too hot of a spark plug right? Could be that the plug couldn't dissipate the heat from combustion efficiently enough and warped or burnt off the electrode entirely....Checking the plugs is a good place to go from here...could definitely be the cause of the loss of power and poor idle... Ruling out burning oil, burning coolant, over heated or incorrectly gapped plugs is as easy as checking your spark plugs.
Stopping your engine with the clutch shouldn't hurt anything, in my opinion. No different than accidentally stalling at a stop light...except it wasn't an accident.
Stopping your engine with the clutch shouldn't hurt anything, in my opinion. No different than accidentally stalling at a stop light...except it wasn't an accident.
Intermediate
Joined: Jun 2006
Posts: 47
Likes: 0
If your running a good performance plug for short drives a hot plug is what you would want...using that same plug for a 60 mile highway drive would probably do exactly what your describing...But there are guys on here who know a lot more than me
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Drifting
Joined: Sep 2007
Posts: 1,572
Likes: 51
From: Wichita Kansas
Considering or assuming you never changed anything including the type of driving I would suspect the timing changed. Hopefully just a loose distributor hold down. The engine may have ran hotter and had detonation on shut down due to an advanced timing and the white smoke on re-start could have been from the hot shut down in a humid climate causing humidity accumulation in the exhaust.
Check the timing
Racer
Joined: Aug 2006
Posts: 359
Likes: 0
From: PYOTE BOMBER BASE TEXAS
I was blowing white smoke out the tailpipes one day...car was running badly...looked about and around ...nothing checked out wrong...except that the choke plate on the carb. had become jammed closed...had to force it to open...ran smooth and no white smoke...but rebuilt the carb as soon as possible...
Last edited by TEXASDESERTVETTE; Aug 14, 2010 at 03:38 PM. Reason: and a distributor replacement later on
Thread Starter
Racer
Joined: Jun 2009
Posts: 409
Likes: 3
From: St. James, NC
Pulled the plugs, all have a lot of carbon; this is not a big surprise because the mixture was on the rich side. Couple plugs on left side were a little wet but I can’t tell if it’s from coolant or oil. Now that the engine is cool the recovery jug level is almost empty…was 2/3 full when I started for the day. Probably head gasket??? 
Thread Starter
Racer
Joined: Jun 2009
Posts: 409
Likes: 3
From: St. James, NC
I was blowing white smoke out the tailpipes one day...car was running badly...looked about and around ...nothing checked out wrong...except that the choke plate on the carb. had become jammed closed...had to force it to open...ran smooth and no white smoke...but rebuilt the carb as soon as possible...
Hoping for easy fixes
Racer
Joined: Aug 2006
Posts: 359
Likes: 0
From: PYOTE BOMBER BASE TEXAS
I recall that it was during the summer...and things happened much like what you described...engine began running on...coughing...a few back-fires...hard starting...bogging down ...lota white smoke out of one side...dreadful gut-feeling...
foul language...Holley carb...Top Tier fuel supplier...the coolant loss issue is unknown as I was having to add more coolant to the system ,( Due to a unknown pin hole leak location in a weld on the new aluminum radiator) but was a concern at the time... Best of LUCK to you!
foul language...Holley carb...Top Tier fuel supplier...the coolant loss issue is unknown as I was having to add more coolant to the system ,( Due to a unknown pin hole leak location in a weld on the new aluminum radiator) but was a concern at the time... Best of LUCK to you!
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
I would drain the gas and put some fresh gas in from a better station.....Like Shell or Chevron, slap in some new plugs and see what it does.....If it is still smoking and losing coolant, it probably popped a head gasket. Was the timing set correctly? Maybe it was detonating and it got the head gasket.... You won't always get water in the oil and vice versa with a blown head gasket....depends on where the gasket let go....
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
Pulled the plugs, all have a lot of carbon; this is not a big surprise because the mixture was on the rich side. Couple plugs on left side were a little wet but I can’t tell if it’s from coolant or oil. Now that the engine is cool the recovery jug level is almost empty…was 2/3 full when I started for the day. Probably head gasket???
Drifting
Joined: Aug 2005
Posts: 1,682
Likes: 3
From: League City TX
Pulled the plugs, all have a lot of carbon; this is not a big surprise because the mixture was on the rich side. Couple plugs on left side were a little wet but I can’t tell if it’s from coolant or oil. Now that the engine is cool the recovery jug level is almost empty…was 2/3 full when I started for the day. Probably head gasket???
I would start the car and run it for long enough to pressurize the cooling system.
When it gets cool enough, pull the plugs that were wet and crank the engine over.
If any significant amount of water is leaking into the cylinder it will blow it out of the plug hole when you crank it.
Water in the cylinder = Bad head gasket (unless the head is cracked
)
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
Pulled the plugs, all have a lot of carbon; this is not a big surprise because the mixture was on the rich side. Couple plugs on left side were a little wet but I can’t tell if it’s from coolant or oil. Now that the engine is cool the recovery jug level is almost empty…was 2/3 full when I started for the day. Probably head gasket???