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3.9 Classic tapping


DC_

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Hello all, got a query for you all.

As our MAC4x4 rally is coming up at the start of March, i'm a little concerned about the RRC giving off a tapping/ticking noise now and again when she's driving.

I did an oil change 2 weeks ago and that seemed to cure it but it returned last night and was a little louder than usual.

Can you tell me how dangerous it is or is there a way to ease it for my rally as i don't have that much time to do any big jobs.

I have heard of tappet sealant, would this be worth a try?

Blooming Landies!!!

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My thoughts went towards an exhaust leak at the manifold but you say an oil change cured it for a while so that would rule it out.

What oil did you use? For this older engine I would think you need to use 20/50.

If it is a tappet type noise then you may be losing a cam lobe which is quite common. The noise is there because the wear is outside of the range the hydraulic tappet can deal with.

Steve

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Ok got a little more time to explain a bit more about the noise/problem.

After the car was sitting for a week or more unstarted, when firing it up there would be a ticking noise present in relation to the revs. Ticking gets faster as the engine revs more.

After letting it idle for a minute, the ticking would go away.

Now and again when driving the ticking would be present but louder as the revs where higher. After a short drive or pulling over, the ticking would go away agian.

Done an oil change with CLASSIC motor oil, 20w/50 (duckhams me thinks as it was green) as stated in the book of lies.

Ticking and engine sounded good, but last night the ticking returned and lingered longer than ever before.

I haven't been out today due to time.

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It could just be a lazy/sticking hydraulic lifter. When the engine is stopped some of the valves will be held open which is applying load to the lifter. While sitting there the oil can bleed out of the lifter. When you come to restart that lifter will have play and rattle until the pressure builds up again in the lifter.

That does not however explain why it will start again whilst driving.

Steve

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Guess it's auto shop for me tomorrow then and give it a go. If it works i'll be a happy chappy. Got a 1600 mile trek coming up in a couple of weeks.

Many thanks for the responses

DC

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sounds like a sticking follower but i would be inclined to firstly put a flush though it the best is forte products one tin is all you will need add to a warm engine allow to run at idle for 10 min then raise the revs to 2-2500 rpm for 5min IT wil not harm the engine allow to idle again for a few min then drain and replace the filter as well in any v8 i would also use 15/40 oil mineral run it would again and see how it sounds if it is worse then you will have a follower/cam problem

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If the lifter treatment fails then i'll prob go for the flush and then the new oil. Would be eager to get feedback on the type of oil though. Seems there's alot of different opinions.

Many thanks for the responses so far folks. Appreciate them all.

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  • 3 weeks later...

Update:

Now believe it is actually the leaking manifold to head.

After doing 1200 miles on the MAc 4x4 Challenge. I noticed a pattern developing. When on petrol, there was no ticking, when on gas, ticking returned. So, looks like there is a stud to head that won't tighten fully, looking into the engine bay from the front, it's on the right hand side (where the ticking is coming from) Stud won't tighten fully so this may be the cause.

The gas would expand the the cylinders and exhaust more due to more heat from burning on gas...............................i'm sure one of you guys in the know will correct me if this is not right.

So..........................need to try a few things to get that stud tight. Longer stud? Suggested re-drill and re-tap? (much more of a barstewart to get it drilled) chemical metal to hold stud in place and put a nut on it?

Your thoughts again greatly anticipated.

DC

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Update:

Now believe it is actually the leaking manifold to head.

After doing 1200 miles on the MAc 4x4 Challenge. I noticed a pattern developing. When on petrol, there was no ticking, when on gas, ticking returned. So, looks like there is a stud to head that won't tighten fully, looking into the engine bay from the front, it's on the right hand side (where the ticking is coming from) Stud won't tighten fully so this may be the cause.

The gas would expand the the cylinders and exhaust more due to more heat from burning on gas...............................i'm sure one of you guys in the know will correct me if this is not right.

So..........................need to try a few things to get that stud tight. Longer stud? Suggested re-drill and re-tap? (much more of a barstewart to get it drilled) chemical metal to hold stud in place and put a nut on it?

Your thoughts again greatly anticipated.

DC

Explain what you mean by 'stud won't tighten fully'.

Are you using studs or bolts?

Does the stud/bolt just keep turning as in the thread is stripped in the head?

Your talk of chemical metal implies the thread is stripped. Chemical metal will not fix this.

Sounds like the head needs to be drilled and tapped oversize and a Helicoil fitted.

Steve

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Hi Steve, stud/bolt will keep turning even when fully home and will not tighten.

Suggested that the Helicoil option would be a total nightmare to get the drill into the head as there is very little room there.

I'm using the UNC 3/8

Update so far.

Tried a longer stud/bolt to see if it would make a difference. Don't really know if it was slightly larger but it did tighten.

due to lack of time, i only managed to check half the studs to make sure they were all tight. After a test drive on the LPG it started ticking again after about 6-7 miles.

So, after a lil inspection, i noticed the manifold to Y piece isn't fully home, so that's another job i'll need to do after i make sure the studs are all tight. Will also inspect the gaskets if this fails.

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Cheers Fridge.

To be honest i'm kacking myself everytime i turn the Stud/bolt.

I've put a good few washers on it to make it just slightly (very) longer than the original UNC's that are in. Give us a loan of your magic wand and i'll post it back to you ;)

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The hole will not need drilling as the Helicoil tap is only one size up. Get a block of ali or steel and drill a hole in it that is just bigger than the Helicoil tap. Hold this against the face of the head and use it as a guide to keep the tap square to the face.

Steve

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