K-series con rod change

nomzamo999 · 22nd July 2019, 10:44

Hi all.
Has anybody here successfully changed a con rod on a 1.8 petrol engine without removing the crankshaft or cylinder head?
I have a bent con rod after a hydro-lock which is causing a persistent misfire on cylinder 1.
Ideally, I'd like to drop the sump, disconnect piston 1 at the big end, and then just withdraw enough of the piston to get at the gudgeon pin.
Does anyone know if there is enough clearance around the crankshaft to allow this?
If not, I'm looking at a full engine strip-down, which means the car will be off the road for quite a while.
I've only ever mucked about with crankshafts & pistons on a 1275 Mini engine which was out of the car, so unsure of the practicalities of doing it engine-in.
Any advice would be gratefully welcomed, thank you.

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milford man · 22nd July 2019, 10:56

You won't get the pin out of the Piston. They are a press fit in the con ron. You will have to take the head off.

Regards John

nomzamo999 · 22nd July 2019, 11:05

Quote:

Originally Posted by milford man

You won't get the pin out of the Piston. They are a press fit in the con ron. You will have to take the head off.

Regards John

Thanks, that's what I was afraid of.
The head gasket seems to be the best part of the engine right now, so I didn't want to disturb it if avoidable.
Maybe I'll put up with the misfire for now, and look at building an engine with a few more BHP in the future.
It only really becomes an issue with older spark plugs, as no.1 burns away a bit, causing the misfire when combined with the slightly lower compression.

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Sheraton · 22nd July 2019, 11:26

Out of curiosity - How did you diagnose a bent Con-Rod ?

Paul.

nomzamo999 · 22nd July 2019, 11:42

Quote:

Originally Posted by Sheraton

Out of curiosity - How did you diagnose a bent Con-Rod ?

Paul.

Take the spark plugs out.
Put a dowel into the hole & let it rest on the piston top.
Slowly hand crank the engine and mark the lowest point on the dowel.
Repeat for all cylinders and if one goes lower than the others, then the con rod is bent.

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rrobson · 22nd July 2019, 14:29

Just get a good used piston and rod. Pins will come out with a press and a little heat doesn't go amiss.
The crank can stay in but pistons won't come out the bottom and even if they would, you'd have a job compressing the rings to get the new piston in.

If your planning on keeping the car do a complete strip and inspection, you'll probably find it wants a liner or two anyway

22nd July 2019, 10:44	#1
nomzamo999 Posted a thing or two MG ZT Join Date: Mar 2013 Location: St Blazey, Cornwall Posts: 1,143 Thanks: 178 Thanked 82 Times in 79 Posts	K-series con rod change Hi all. Has anybody here successfully changed a con rod on a 1.8 petrol engine without removing the crankshaft or cylinder head? I have a bent con rod after a hydro-lock which is causing a persistent misfire on cylinder 1. Ideally, I'd like to drop the sump, disconnect piston 1 at the big end, and then just withdraw enough of the piston to get at the gudgeon pin. Does anyone know if there is enough clearance around the crankshaft to allow this? If not, I'm looking at a full engine strip-down, which means the car will be off the road for quite a while. I've only ever mucked about with crankshafts & pistons on a 1275 Mini engine which was out of the car, so unsure of the practicalities of doing it engine-in. Any advice would be gratefully welcomed, thank you. Sent from my Pixel 2 XL using Tapatalk

22nd July 2019, 14:29	#6
rrobson I really should get out more....... 75 tourer cdti, MG ZS 180, nissan terrano & 1.8t rover 25 Join Date: Feb 2010 Location: Pontefract Posts: 2,643 Thanks: 17 Thanked 295 Times in 218 Posts	Just get a good used piston and rod. Pins will come out with a press and a little heat doesn't go amiss. The crank can stay in but pistons won't come out the bottom and even if they would, you'd have a job compressing the rings to get the new piston in. If your planning on keeping the car do a complete strip and inspection, you'll probably find it wants a liner or two anyway __________________ How to view a car - everything you need to help you inspect a used car VIS motor tester avalible to local members Injector removal tool and auto gearbox pressure tester now available

22nd July 2019, 10:56	#2
milford man Gets stuck in Jaguar XE Prestige Join Date: Oct 2010 Location: Coventry Posts: 540 Thanks: 155 Thanked 109 Times in 101 Posts	You won't get the pin out of the Piston. They are a press fit in the con ron. You will have to take the head off. Regards John

22nd July 2019, 11:26	#4
Sheraton Posted a thing or two Rover 75 1.8t Join Date: Oct 2015 Location: Edinburgh Posts: 1,377 Thanks: 384 Thanked 409 Times in 267 Posts	Out of curiosity - How did you diagnose a bent Con-Rod ? Paul.