Hydrolock - Compression test results
Thread Starter
Instructor
Joined: Dec 2016
Posts: 144
Likes: 27
From: Kingwood TX
St. Jude Donor '17
Hydrolock - Compression test results
I hit some high water the other day during a brief heavy thunderstorm/flash flood and my Callaway Honker sucked water into the engine and killed it. I had it taken to a shop, and after draining all the water out, they ran a compression test. It showed 5 of the cylinders were at 170. Two other cylinders were at 150(13% off), and another cylinder was at 130(30% off). The shop said that it was completely fine since even at 130 it was well above GM's minimum specs, but I was always under the impression that the cylinders should always be within about 10% of each other, regardless of the reading. After driving it for the past week or so, I may be paranoid, but the car feels "off." It's also running about 15 degrees hotter than it was prior to the incident.
Since this was covered by insurance, is it reasonable to have them check out the engine again and maybe run a wet test, or am I just crazy?
Thanks
Since this was covered by insurance, is it reasonable to have them check out the engine again and maybe run a wet test, or am I just crazy?
Thanks
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Eggxactically. And with the one year anniversary of hurricane Harvey just in our rear view mirrors, there ought to be an insurance adjuster or two around with "water in the motor" experience. Stay on top of it and find the problem as quick as you can. Adjuster guys hate it when you make a claim weeks after the damage date.
Thread Starter
Instructor
Joined: Dec 2016
Posts: 144
Likes: 27
From: Kingwood TX
St. Jude Donor '17
Thanks, guys. I appreciate your input. I spoke with my insurance company today, and they requested that I take it back to the shop who did the original service first. I'll be getting back with them to request a leakdown test and see how that goes.
Pro
Joined: Jun 2015
Posts: 627
Likes: 110
I hit some high water the other day during a brief heavy thunderstorm/flash flood and my Callaway Honker sucked water into the engine and killed it. I had it taken to a shop, and after draining all the water out, they ran a compression test. It showed 5 of the cylinders were at 170. Two other cylinders were at 150(13% off), and another cylinder was at 130(30% off). The shop said that it was completely fine since even at 130 it was well above GM's minimum specs, but I was always under the impression that the cylinders should always be within about 10% of each other, regardless of the reading. After driving it for the past week or so, I may be paranoid, but the car feels "off." It's also running about 15 degrees hotter than it was prior to the incident.
Since this was covered by insurance, is it reasonable to have them check out the engine again and maybe run a wet test, or am I just crazy?
Thanks
Since this was covered by insurance, is it reasonable to have them check out the engine again and maybe run a wet test, or am I just crazy?
Thanks
Advanced
Joined: Sep 2016
Posts: 76
Likes: 10
Very good chance that you have a bent rod, I have personally replaced several engines (not Corvettes) that hydro locked due to bent rods. On pent roof combustion chamber engines you can check piston height through the spark plug hole. Two insurance companies just paid us to replace the damaged Piston/Rod. I have also witnessed rod bending from blown head gaskets that is clearly visible when the heads are removed on a wedge type combustion chamber engine. If run without repair you will soon ruin the connecting rod bearing and possibly the crankshaft as the rods also tend to twist as they bend. With that much variation in cranking pressure you will soon have misfire codes as well. Certainly retain all records if the insurance company refuses to proceed to your satisfaction.
Last edited by Turbokraft; Sep 5, 2018 at 08:40 AM. Reason: grammar
Thread Starter
Instructor
Joined: Dec 2016
Posts: 144
Likes: 27
From: Kingwood TX
St. Jude Donor '17
Very good chance that you have a bent rod, I have personally replaced several engines (not Corvettes) that hydro locked due to bent rods. On pent roof combustion chamber engines you can check piston height through the spark plug hole. Two insurance companies just paid us to replace the damaged Piston/Rod. I have also witnessed rod bending from blown head gaskets that is clearly visible when the heads are removed on a wedge type combustion chamber engine. If run without repair you will soon ruin the connecting rod bearing and possibly the crankshaft as the rods also tend to twist as they bend. With that much variation in cranking pressure you will soon have misfire codes as well. Certainly retain all records if the insurance company refuses to proceed to your satisfaction.
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Advanced
Joined: Sep 2016
Posts: 76
Likes: 10
30% is more than a little low but none of us know how the testing was conducted. If done properly that is not within spec. If the test is correct I suspect you will soon see a P0300 or P0305. Keep records and enjoy your car.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,591
Likes: 4,055
From: Cape Coral, Florida
Yeah, I'm definitely going to have to keep my records on this. It was completely replaced last year with a new factory LS3 with a warranty and only has 15,000 miles on it. The car has spent the last few days in the shop, and I am to pick it up this Saturday. Both the shop and the insurance company seem to be insistent that the car seems fine. I honestly don't think they did any real test other than test drive it. They just keep saying that they talked to a tech at GM, and that while cylinder 5 is "a little low", it is well within spec. According to them, the only way I could possibly tell a difference is if I were drag racing. In which case, I'd maybe be a tenth slower in the quarter... Even though my car is an '08, that engine is only a year old. It was completely replaced last year with a new factory LS3 with a warranty and only has 15,000 miles on it.
compression test" even better with a DSO. You could get a TDC locator this this and see how many threads are exposed on each cylinder when rod is at TDC...these things are cheap..I keep a few around !!