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Hot Rods Damage a motor by hydro-lock

Discussion in 'The Hokey Ass Message Board' started by blazedogs, Apr 9, 2020.

  1. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    Hope I used the right term Hydro- lock. I damaged a a engine some time ago and seldom see this happen or talked about. ( Oil) had accumulated on top of the pistons or ( gas) and you force the engine to turn over when all the valves are closed thinking you have a low battery or what-ever, not realizing at the time the cyls. are actually flooded. The result damaging the bottom end, a rod or whatever. Yup I did just that in my younger yrs.. Gene
    Hnstray likes this.
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,329


    While driving, or just cranking the starter?

    Pull the plugs, and compression check each cylinder.

    It is hard to do major damage with just the starter.
  3. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    Cranking the motor
  4. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    It was a tired motor to begin with but it surprised me that that could happen...

  5. It can happen very easy,,,,usually from water in a cylinder from a cracked head ,,or head gasket .
    You shut the engine down and water accumulates from the head,,,or gasket .
    The next morning,,,,bam,,,it will really rock the vehicle.
    It will literally feel like someone hit the body with a sledge hammer.
    Usually a bent rod is the result,,,sometimes worse .

  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,329


    I have only ever had it stop the starter cold.

    Just pulled the plugs, cleared the cylinders, and continued on.
    belair and bchctybob like this.
  7. Budget36
    Joined: Nov 29, 2014
    Posts: 6,711


    I've been lucky over the years, but did help a buddy tearing an engine down that had a bent rod because of hydro-locking I did have a OT vehicle that had it, but got it fixed (big head gasket leak) before dame was done.
    Lloyd's paint & glass likes this.
  8. Sure does happen.
    But it depends on where the offender cylinder is in the firing order and what’s going to fire next or infront of the offense. Yep feels like a low battery and bang you broke something.

    If the offender is locked without firing cylinders behind it then it’s usually just a stopped starter.
    town sedan and egads like this.
  9. 14E13BFA-8D22-4E27-8B1B-736E2C272B2B.jpeg F5F79B0A-8A07-4504-8256-7D42CF9EC076.jpeg More times than not ,,you are right,,usually just stop the starter .

    Several years ago ,,my dad had it happen in his old Chevy late model truck .
    It locked up,,,but then came loose,,,,,after it fired up,,,had a bad knock,,like a rod bearing .
    He thought it just needed a rebuild,,,,it already had a lot of miles on it,,,about 270,000 .
    Anyway,,decided to tear it down,,,,,# 5 rod was bent pretty good .
    As a matter of fact,,,I still have it,,,here it is .
    As they say here,,,pics,,,of it didn’t happen !

    Last edited: Apr 9, 2020
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  10. blazedogs
    Joined: Sep 22, 2014
    Posts: 470


    I should have added prestone or water besides oil or gas. It never crossed my mined that this had happened before I hit the starter
  11. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,319


    Many years ago went to start my 57 Fuely-it spun and locked up with a jolt--#1 cylinder Yep bent rod! Early Fuel injection units were prone to leaking by. Installed an electric solenoid in spider line--no more problems--It ran fine that way for another 36 years til I sold it.
    town sedan likes this.
  12. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,329


    I guess my poverty, leading to having crappy batteries, and weak starters, actually saved me several engines!
  13. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,414


    I used to work at the Fred Harvey garage at the south rim of the Grand canyon and did a lot of wrecker service calls. One of the big issues was people 's cars were set up for lower elevation and they would come up to the canyon and crank their cars and try to drive away without letting them warm up. Remember this was when cars had carbs and not injection. the car would drive about 10 feet and die and they would try to crank them up again but the choke was slammed shut tight and they would flood the engine and run the battery down. we had a diesel bus battery mounted on the wrecker and it would crank anything. I have seen a few bent rods from the motor being hydro locked with gas and I have seen some timing chains jump from trying to crank flooded engines.
    We have even had engines that were so worn out that we had to push them with the wrecker to get them going and tell them don't shut it off until you get to lower elevation.
    I remember one particular big block Mopar that was badly flooded and I warned the owner that we needed to tow the car to the shop and pull the plugs . He thought I was trying to rip him off for a wrecker bill and a service charge,but he finally let me tow it in and I pulled the plugs and charged his dead battery . When I pulled the plugs gas ran out on the floor. I pulled the coil wire and cranked it over and gas shot about 6 feet past the fenders. After we dried everything up and changed the oil. I put a new set of plugs in and it cranked right up. He watched the whole procedure and gave me a 50 dollar tip for saving not only his trip, but his engine.
  14. I'm going through something does a bent rod sound like?(feel like)
  15. egads
    Joined: Aug 23, 2011
    Posts: 1,065


    Iv'e seen nose cones busted off of starter's from hydro locking. Got about a dozen rods on the wall that look like desoto291hemis and worse.
  16. Starlinerdude
    Joined: Mar 6, 2008
    Posts: 148

    from Washington

    The first year the Chevy Duramax Diesel came out they had a slew of warranty engine replacements due to the head gasket leaking coolant into the cylinders and the next time you tried to start it bang broke the crank.
  17. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,452

    jimmy six

    I had a 65 Chevelle that I think hydrauliced at the factory. I bought it with 13k miles and it always had a low reading cylinder on a compression check. Took it apart at 117,000 miles and 1 rod had an “ess” in it.
    Driver50x likes this.
  18. tubman
    Joined: May 16, 2007
    Posts: 5,729


    I had this happen to me once. I put a Pertronix in a boat with an SBC with a Mercruiser Alpha-One outdrive. The Pertronix had a lot more duration than the points, so the engine turned over about half a turn, back-fired, and hydro-locked because it sucked water up the exhaust into the engine. I was lucky; I broke a cheap aluminum roller rocker, but that was it. I replaced the broken rocker, and the engine ran great (after being re-timed).

    Sometimes it's better to be lucky than smart.
    Desoto291Hemi likes this.
  19. bchctybob
    Joined: Sep 18, 2011
    Posts: 3,089


    My kids' GoKart used to do that if you didn't shut off the gas valve. Grab the cord and pull, and just about yank your shoulder out of joint. Lucky me, since it was hard to start when cold I was the one who usually ended up with the sore shoulder. We learned to "back it down" slowly like a nitro engine. And turn off the gas!
    Desoto291Hemi likes this.
  20. deathrowdave
    Joined: May 27, 2014
    Posts: 2,645

    from NKy

    Had an old Harley that would hydro lock , a lot .leaky , pet cock and carb needle . I could not generate enough through kickin it to hurt anything . My Buddy had 36 Chebby Coupe LT1 , 3 deuces . It sat in the rain for a few days , he tried to fire it , spun around , bang ! It stopped cold , he removed the plugs , shot out the water , new plugs fired it drove it for years with a knock from then on .
    Driver50x and Desoto291Hemi like this.
  21. Joe H
    Joined: Feb 10, 2008
    Posts: 1,077

    Joe H

    My buddies 340 Mopar blew a head gasket at 7000 rpm, hydro-locked and blew the piston out the side of the block.
  22. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,047

    from Quincy, IL

    Back in the late ‘60s I was working in a Ford dealer shop and running the wrecker was one of my duties. One rainy Saturday morning I was on a wrecker call up north of town to recover a rolled over dump truck.

    On the way back I saw the new Ford F-600 cab and chassis the shop manager was servicing when I left to get the dump truck. Only the F-600 was now down an embankment and overturned in a field alongside the highway. I think he must have hit the brakes a bit too hard and with no bed or load, the hydro-vac locked the rear wheels on the wet pavement and spun him off the road. I proceeded to the shop, dropped the dump truck and went back to retrieve the F-600.

    Returning to the shop, I dropped the F-600 and attempted to start it and back it into a parking spot. The engine, an FE V8, began to turn over, then just grunted and stopped cranking. It had not occurred to me, until that moment, that while it laid upside down oil leaked into at least one cylinder, maybe more, but the result was a bent rod. Lesson learned!

    town sedan, VANDENPLAS and egads like this.
  23. Back in the early 70s I had a job testing take-out engines in a salvage yard. We sold a 455 Olds to this guy for his gutlass. He was back in a week complaining of a noise in the engine. Had him yank it and bring it to me. Bent #7 rod. We stood behind the engine and I triple-checked another 455 we had. Gave it to him and he was back in another week. Number 7 rod bent in that engine too! I asked to see the car and we drove to the guy's house. The Olds was sitting on the street, facing uphill with a big ol hood scoop on it! It also has one of those 3 sided foam air cleaners sitting on the inner fender! Weather was typical Portland winter weather........rain. Needless to say he didn't get another 455 from us for free.
  24. Last fall, I had a St. Louis County Highway International dump truck come in for poor running and a misfiring cylinder. After running a relative compression test with the laptop, it was determined that cylinder number 5 had very low compression. My thought was that the liner had gotten worn greatly oversized, I had overhauled 5 of them last year up to that point for the same thing. County approved the overhaul and I disassembled the engine. Hmmm, no visual damage, now I’m getting worried. I removed the pistons from the rods and cleaned up the rods. Upon inspection, the number 5 rod was badly bent. There’s our compression loss! The EGR cooler was leaking before the overhaul and County’s own mechanics replaced it, it flooded number 5 and it was at BDC when the driver started it and another cylinder fired off and bent the rod.

    Sent from my iPhone using The H.A.M.B. mobile app
  25. Had it happen at jag on a v6

    right behind the TB was a vacuum line and coolant line side by side.
    Apprentice got them crossed
    Engine stated and ran fine for about 10 minutes, then only what I can describe as a symphony of hammers hitting an anvil..... the engine loaded up then cleared out and ran like a bag of crap, multiple misfires.

    wtf. Started poking around, found the crossed coolant line, suspected hydro-lock.
    Tool the heads off
    Multiple bent valves across almost all cylinders.
    Never bothered dropping the oil pan to inspect further.
    Luckily the car was under warranty.
    So a check engine light, became creative story telling to get the engine covered under warranty.
    All worked out but .... yeah it happens and it’s nuts.
    Truckdoctor Andy and town sedan like this.
  26. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,414


    a bent rod is called Peyronie's . :eek:
    Hnstray likes this.
  27. oldolds
    Joined: Oct 18, 2010
    Posts: 3,166


    This happens to quite a few hot rods that get caught parked in a rain. V-8 car with 2 piece hood and no air cleaner or even with a big chrome one. Rain gets in the split of the hood and into the carb. Air cleaner can be like a funnel runs past the wing nut. Saw it happen a couple times at York NSRA after a rainy weekend.
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  28. GordonC
    Joined: Mar 6, 2006
    Posts: 2,400


    Had a neighbor that drove his Chrysler 300 through a deep puddle during a severe rain storm we were having and he sucked in water and hydro locked the motor. Killed it. Seems the air intake was down at the lower part of the front grill. Had to replace the whole engine to the tune of about $8k.
    egads and Hnstray like this.
  29. Nostrebor
    Joined: Jun 25, 2014
    Posts: 1,185


    My wife had an OT vehicle that we drove for almost a year from purchase before it developed a light knock. When we tore into it we found that a PO had replaced the head gasket, and apparently it had hydrolocked as well. The piston was far short of coming up full stroke. The wrist pin appeared to be the knock, as the crank journal looked fine.

    We didn't have a lot of cash at the time so we replaced one rod/piston/ring set and put it back together. It had much more power, and ran a trouble free 100k before we unloaded it.:p
    egads and town sedan like this.
  30. Actually either one of two things usually happens and destroys something in the motor to relieve the pressure or it won't crank. The culprit is usually water in the cylinder in my experience.

    Deisels used to be the worse but I did have a Cleveland motor come into the shop when I was a kid. my dad sent him to me. I asked him why he didn't just pull the plugs instead of the motor. Then I looked in the back of his truck and he lifted the pan. Number 4 rod broke on the small end.

    It was repairable, the crank was good, the saddles proved out well. but it chewed the cylinder up a little bit so it was a rod and a set of pistons and an over bore.
    town sedan and Desoto291Hemi like this.

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