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Knock, Knock ... Whos There? My Engine


sx2500831

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So I aquired a 1973 GT6 that had been sitting in a barn since 1979. Super long story short. I replaced all hoses and cleaned all the things that needed to be cleaned. Oil looked good and was changed recently. 72 miles into a trip I start to hear a tap noise. After a half mile I pull over to check under the hood. I find nothing. I drivemaybe a total of 5 miles. Again, Long story short, Engine knocks while idle. I pull the oil filter and find sludge and black as tar oil. Not thick but dark. No oil pressure means no oil to the engine. I am going to pull the oil pan and claean it install a new filter and maybe even pour kerosene into the oil fill cap to flush out anymore junk. I hope the knock goes away. I am kind of scared about this but I'm hoping for the best. What oil should I use in it? 1973 GT6 U.S. Model. One huge bonus is that the engine did not over heat. I only drove it 4.6 miles. What do you people think

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For a car that's been sitting so long, it's essential to remove the sump to check for sludge/rust debris. Even if you change the oil hot, the sludge is likely to be stiff enough to remain.  If left, as you use the car, the top layer of sludge gets picked up in the oil, blocks the oil filter hence allowing unfiltered oil to pass via the relief valve to the bearings where they are quickly scored and worn.

This happened to my Stag after only 9 years.

You are having the sump off anyway, drop a couple of the bearing caps off (dont muddle them up) and check the shells, I'll wager you will find them down to the copper   :-/

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Sounds like the big ends are gone and it's time to pull the crank for a regrind and new shells.  :-/
Once it's done you'll know it's good.  :)
You may have discovered why it went into the barn in the first place.....

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The car went into the barn because the owner died in 1979. The engine was completely fine until this sludge oil pressure thing happened. Do you still think I did major damage in 4.6 miles? Thanks for all the input. I just can't wait to get this car going right again.

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I'm naturally pessimistic, sorry!
My Triumph made me so early in our relationship, with the number of engines I blew up! They were all 4-cylinder though, admittedly.
sx, you'd be unlikely to have blown the big ends in so short a distance with no overheating, but I once blew an engine in a 2 mile trip when a piece of piston ring became detached and went right through the mains. Sometimes luck's bad.  :-/
I'd be dropping the sump at least to see what the condition of the bottom end is. But then I AM pessimistic.  :-)

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So i pulled the oil pan off and found that a rod bearing spun. It ovalized the crank to .0015 to .002 off. It also blued the rod in spots. Look like the motor is coming out. While its out we are going to replace all the bearings, grind the valves. Check the piston rings and replace the timing chain. We will replace whatever needs to be done to play it safe.

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Sorry to hear that.  Oddlly, around 1979 was when I blew up my car's original engine.

If you're doing a full rebuild, you can still get the factory shop manual used or new-ish, either from Bentley books' reprint or the factory manual on ebay or via bookfinder.
You should also look at things like Kastner's competition preparation booklet that he wrote for BL's US SCCA participants -  a little port & polish on the head gets good reviews.

You get to skim the head to get a better compression ratio now, if you want.

You might also poke around & see what the camshaft situation is like - I've not been able to complete my GT6 cam research, but if the 2nd-to-last GT6 Mk3 cam was better than the last, or if you can find a GT6+ cam floating around for a flea market price, now would be the time to put it in to get some more fun short of buying a performance cam.  They got better cams everywhere else, but the US GT6+ cam was impressive anyway.

At any rate, treat it like you're never going in there again & you're doing all you can this time!

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I had a shock this evening I run the Spitfire up after a couple of months lying idle.
Usual practice, pump up some fuel, remove ignition wire from coil, spin her over for 20-30 secs, switch off, replace ignition wire, pull on choke - turn key again, engine fires but oil light stays on, push in choke, engine idles slow and gives a little knock, switch off quickly.  Take off pressure release valve - yes, plunger stuck in crank case aperture, remove, clean and replace making sure it moves in and out, try start again this time oil light goes out and all is well again - phew :)

8)

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Not as big a shock as I had this evening. Went for a spin to check carbs and timing were ok after fitting electronic ignition and after 30 mins started popping and farting like a good 'un. Pulled off the main road to have a look and decided it was an ignition problem. Re- fitted the old points etc, no change, plus a horrible noise from the engine. Called the recovery team.
Whilst awaiting their arrival I decided to have a look under the rocker cover and found this...
http://db.tt/itP0X1wW

So, did the rocker seize and drop the rod, or did the rod bend and seize the rocker?

Bugger :(

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I've had a push rod jump out when giving a flat four that I knew needed the clearances adjusting some welly from trafic lights and had dropped the engine out before noticing the push rod was out - bugger.

It looks like you have plenty of oil up top, has the rocker seized then, or were your tappets rattly and you gave her too much boot :-/.

8)

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Looks like a blocked oil way. Rocker number three seized completely, the rest are scored at best. Four or five bent push rods. All replaced now and I've cleaned out the path twixt head and rocker. Bit ofa pisser really as I'd not long since replace the rockers and shaft,as the old shaft had no end bungs, so no oil was passing through the rockers.

Lesson learned now though.

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