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hydrolock - diagnose bent rod
Posted: Thu May 29, 2014 2:58 pm
by cruiser60series
Hello all, I tried to start my car (HJ47 2H) after sitting for about 3 weeks through some brutal rain and somehow water got into the air box and into the air intake. It fired a couple of times (ran for less than a second) at first but then wouldn't start, rpm probably didn't get over 1000. Compression test shows all cylinders as cactus <10:1, I assume head gasket is completely farked. I got all the water out as best I could straight away and am in the process of getting the head off.
What I want to know is once I get the head off will it be easy for me to measure the stroke and determine if I have a bent rod, or could a possible bend be more minor and not as easily measured as that. Also since the engine didn't get up to high torque/rpm is it even likely I have a bent rod? Motor turns over fine with the starter motor at the moment.
Any advice appreciated.
Re: hydrolock - diagnose bent rod
Posted: Thu May 29, 2014 3:58 pm
by mundy
I'm not to familiar with the 2h but easy way is with the head of make sure each piston comes up level with the top of the block. If you have one that sit lower you may have a bent rod.
The most precise method is to knock the sump off as well and remove each piston and rod assembly and then you can check and re install them.
But from what you describe I would say the gasket let go so you shouldn't have any major damage.
Re: hydrolock - diagnose bent rod
Posted: Thu May 29, 2014 8:43 pm
by RED60
cruiser60series wrote:
What I want to know is once I get the head off will it be easy for me to measure the stroke and determine if I have a bent rod, or could a possible bend be more minor and not as easily measured as that. Also since the engine didn't get up to high torque/rpm is it even likely I have a bent rod? Motor turns over fine with the starter motor at the moment.
Any advice appreciated.
Measuring the stroke will not tell you if you have a bent rod..... take head off, turn the motor over by hand (spanner on the crank pully or similar)... get each piston to its tdc and measure (with a dial gauge) how far below/above the top of the block each one is..... if you have anything more than maybe .005" difference between them I'd be looking for a bent rod on the lowest one..... I have seen bent rods caused by a starter motor only, though a running engine does a better job..... I would think if it cranks but doesn't start there is some other problem, tho a bent rod wouldn't help, it still should start.
Re: hydrolock - diagnose bent rod
Posted: Thu May 29, 2014 11:11 pm
by cruiser60series
OK will report back when I use a dial gauge on the pistons this weekend when I get the head off. I assume the only reason it won't start now because the head gasket is buggered and there is not enough compression, regardless of bent rods.
Re: hydrolock - diagnose bent rod
Posted: Fri Jun 06, 2014 7:46 pm
by RED60
cruiser60series wrote:OK will report back when I use a dial gauge on the pistons this weekend when I get the head off. I assume the only reason it won't start now because the head gasket is buggered and there is not enough compression, regardless of bent rods.
And the answer is....................
Re: hydrolock - diagnose bent rod
Posted: Fri Jun 13, 2014 1:49 pm
by cruiser60series
All good I think. It was a little hard to measure as each time I picked up and re clamped the gauge onto the block I could of nudged the arms that set it in place. But I believe that they were all within about 0.1mm (4 thou) of each other. Head has been reconditioned is now back on/torqued up. Need to put in injectors and I can then retest compression.