S/V/C70 Hydrolocking motor

Hi all so I have had a fun few days of stressing out i thought I broke my motor good in 1997 V70 T5, i was messing around changing injectors trying to diagnose a fuel trim fault and some how ended up filling cyl 4 full of fuel think injector may have stuck open. So after I primed it to check for leaks I cranked it it fired and then a loud bang and it stopped i tired to restart and it was locked solid.

My first though was it had sucked in a rag i had in the intercooler into the intake jamming the valves. no rag found, after scratching head for a bit I pulled the plugs and has alook see with my bore scope all ok until I found cyl 4 full of fuel. I wound it over and pumped it out it make a horrible noise so I though I had bent a rod or maybe a valve.

I let it sit over night as I didn't want to do more damage the next day I would the engine over by hand with a 32mm fan hub spanner its all I had I think the crank pully nut is 30mm but all my tools are 2000km away at work.( i have a bore scope at home but not A half inch socket set go figure and winding it over with a spanner by hand sucked) I crudely measured each piston at its highest point through the spark plug hole they were all pretty close about 37mm to the top of the spark plug thread. So I though I would risk trying to start it. It did start and idled after a while lots of smoke and has a mis every now and again I only rand it for 30 sec max.

I can hear metal rating around so I pulled the starter it has sheered a tooth of the drive stater is only a few months old and a genuine bosch it cost me a packet so I will have to source a new drive and rebuild it. I will have to try and fish the tooth out as i can hear it in there. The noise it makes now is significantly less when it starts ( I fitted a spare starter i had)but there must be a bad spot in on the ring gear now not much I can do about that as its slightly noise but not bad.

At this stage its off to a proper mechanic next week not me for a look over and a compression test to me sure if it stuffed or ok.

So my question is it there anything I should be specifically looking at or for damage besides compression test possibly leak down test? And or why the injector stuck on flooding the cylinder? I do understand how injectors are fired but never seen them stick open before

I doubt the valves are bent as they would of been closed to hydraulic the cylinder

Also if its not a write off I am going to buy a new set of injectors as a precation even tho I had my set cleaned and serviced they must have a fault

Any thoughts or input would be greatly appreciated from the more technically minded than me👍


  • VolDanVolDan @VolDan Launceston,Tasmania

    Have you done the compression and leak down tests?

    Years ago I had a white block with burnt exhaust valves, took a while to diagnose.

    More recently on a different white block, some similar issues caused by unmetered air on the intake side.

    No idea on starter gear/mesh noise issues.

    Static timing as a double-check?

  • I don't have the tools for a comp or leak down test that why a trip to a mechanic. In the last picture the starter is missing a tooth that was the main noise. Yer I didn't think of timing check I might have to look up how to time a while block. Lol the last engine I think set the timing on was a Holden 202 many many moons ago lol thanks VolDan

  • SpacSpac @Spac Canberra-ish.
    edited May 1

    If you can’t measure the difference in piston height, then the rod is likely fine.

    A compression check is needed to confirm.

    Injectors can and do stick open, and this seems to be your problem. If you are feeling brave, you can swap the injector with another and see if the problem moves (it almost certainly will).

    Basically, it sounds like you have come to the correct conclusions for the correct reasons.

  • Does any one know if there is an inspection plate on the bottom of the AW 50-42le that you can remove to see to see them bottom of the fly wheel and inside the bell housing?

    I want to have a good look in there but though I would ask before going to all the effort to put on stands in the drive and find out there nothing there

  • Does any one know if there is a removable plate?

  • I've never noticed one mate, I've removed a few boxes and they are pretty 1 piece,

  • Thanks Jimbo 👍

  • edited May 1

    No inspection plate on the bottom but pretty sure you can get a look at the ring gear/flex plate above the driver's side axle. That's where you undo the torque convertor - flex plate bolts when removing the gearbox

  • Cool thanks Tim I will put it on stands tomorrow and have a squizz and see if there are some teeth floating around in there and look at ring gear thank for all the help Gentlemen

  • I moved the car onto a trailer this morning and I think I found the missing tooth of the starter motor its now inside the torque converter or transmission 😔 well its a guess but the trans dumped its life jucie in the deck from 30 sec of running at least the motor is sounding good lol

  • So engine and gear box is coming out we measured the piston heights corectly with a dial guage not my home made vernier setup but all are with in a coupe of thous so no bent rods yay.

    we tested all injectors and #4 injector and its stuck open so there is the culprit (5 new bosch greens pls sir) still not sure if the auto has a hole in it but when she comes out I will know. Something Is leaking its life juice at a rapid rate

    Good time to fix the leaking steering rack replace the sub frame bushes with kaplhenke Delrin ones and replace the sway bar bushes

  • I probably should of started a thread on my never ending money pit of a V70 T5 lol

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