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MG MGB GT V8 Factory Originals Technical - Engine Clicking Noise

I have a noise...

It sounds (to me) like a lifter. It's a metallic tapping sound coming from the drivers side bank of cylinders. I have an exhaust leak on the same side, but this is different. I hear both sounds independent of each other.

As the engine warms up the sound becomes worse and worse. It's really starting to worry me, but the car seems to run well. The idle is ok, and it doesn't seem to stutter while driving.

I removed the valve covers, and even removed the valve train and inspected it, and I didn't notice anything out of place. All the pads that hit the valve stems were still there. None of the cups that the push rods sit into are missing either.

Fresh rebuild of a 4.2L.

Suggestions?
Justin

Welcome to the club. Mine started doing the same, first slightly then gradually got worse. I thought it was something in the valve train and as part of another job I did a top-end rebuild including new cam and hydraulic lifters. I couldn't really tell how badly the cam was worn, but the lifters were showing virtually no dishing on the cam face after some 70k miles (I change my oil and filter every 3k and use a pre-change flush as often as not). Checked the pre-load with the new followers and whilst there was quite a bit of variation it was within limits according to popular opinion, and in any case that is what hydraulic lifters are for - take account of a wide variation in clearances. I was quite gutted during the first run of the engine to bed in the cam to find it start tapping at exactly the same point in the warm-up and the same noise as before. A friend had a standard engine rebuilt from scratch and found exactly the same thing. I took my car to a quality rebuilder and he said he didn't know what was causing it and he couldn't guarantee to clear it during a rebuild. Since then I have discovered several things. One is that if I go on a steady run of a couple of hundred miles or so at motorway speeds it will stop. But when I start doing short journeys again it will eventually come back over a period of several days or weeks. The more miles I do on the run the longer it takes to come back. A month or so ago I did an 800 miler, and it is still silent so far. Another is that with the rocker covers off and forcing a feeler gauge into and out of the rocker to valve gaps, there is no change in the noise whatsoever. A third is that using a listening stick on each rocker in turn there are none that are making a huge amount more noise than the others, but when listening to the ones nearest to where the noise seems to be coming from (front right-hand side in my case) it is slightly noisier but muffled. The fourth is that when driving along I find that by minute changes of the throttle I can make the noise change, even though the throttle changes are way to small to affect the speed of the engine or car. The latter three of these lead me to believe it can't be the valve train, as the conditions are diametrically opposed to what one would expect. I'm beginning to think it is a little end, possibly with a restricted oil supply, and on shorter journeys at lower speeds it is getting starved of oil. Or possibly a loose liner, but they are supposed to be clamped between tabs at the bottom of the bores and the heads, and someone with a lot more experience of these engines than mee says when it *has* been liners it causes major cooling system problems. I wish now that when I did the top-end I'd had the sump off as well and pulled the pistons and con-rods as I might have discovered the cause. As it is I'm planning to change the big-end shells soon (just coming up to 100k since the last change, 200k in total) but don't really want to take the heads off again.
Paul Hunt

I called Glen Towery and told him I was having a ticking problem with a 4.2L and he immediately said "You had a liner shift in the block." He then began to describe the sound to me and he was dead on. (Sounds like there's a marble floating around inside the engine)

He suggested my options are to either replace the block, or resleeve the cylinder and use one of those top hat sleeves. Resleeving sounds good, except it doesn't guarantee that other sleeves won't eventually slip.

I thought about going in from the bottom and tack welding the sleeve to the block, but Glen didn't seem to think that would get me anywhere.

It's worth noting that once I get the engine much above 200 F I have a real hard time keeping it cool. In my previous 3.5L motor I had a hard time getting it up to temp, so I know my radiator and fan setup is effective.

I'm getting married in 57 days, so I'm going to enjoy the rest of my summer and figure out what to do in the winter.

Glen's number is 302-734-1243. He's amazingly good at diagnosing problems and when I've needed parts, he either has it, or can get it. I've worked with him for 8 years and am always amazed at how much knowledge he has about these things.

Call him if you need anything.
Justin

Justin

"I'm getting married in 57 days"

Congrats, Justin!
Carl Floyd

Thanks!

I'm pretty excited! I'm hoping we can run off in the B to our "selected evening destination" but we'll have to wait and see. This ticking noise could be the end of me.
Justin

Justin,
Getting married you say.....Way to go! Does this mean you're going to bring your new bride to the British V8 show in NC next year?.....by then, it could be considered a second honeymoon.
Graham Creswick

I was thinking about this. Try changing the thermostat For the cooler 82 degree one, with the different heat coefficients, Al & Fe, it might be enough.

Justin, remember to keep saying, "women must have a house, men must have an MGB"
Peter

Assuming that it's a liner shift, perhaps a new head gasket may help clamp the liner down tighter. I'm thinking of something like the Premium Fel-Pro PermaTorqueSD gaskets - if the flame seal bears against the top of the liner, this might work.

Wayne
Wayne Pearson

That's a composite gasket right? I'd hate to lose half a point of compression, but if it helps the situation, I may not have a choice.
Justin

If your rocker post is shimmed, to get the correct pre-load, you may have to adjust these if you go to a composite gasket, but it's worth the effort.
Allan

You could take the difference of compressed thickness of the two different gaskets and have that amount milled from the heads. I'm only guessing, but it should only be .020-.030 inches - couldn't the heads handle that much? I'm not really familiar with these engines, so I'll defer to the experts.

Wayne
Wayne Pearson

A neighbour fitted composite gaskets to his Range Rover in place of steel shim but had to go back as it wouldn't pull the skin off a rice-pudding. I wouldn't skim the head to be able to use composition, and unless the liner was in the fully down position when you fitted them I can't see it would help anyway. Composition need a particular installation process if they are to bond and not leak. One person I spoke to with the same problem reckoned it *was* a liner in his case, he removed the sump and put thread seal round the bottom of the liner and that cured it.
Paul Hunt

See that's what I'm talking about. I keep wondering "why can't I go up from the bottom and try to secure all the liners with some sort of sealant?"

My oil pan gasket is leaking so I have to take the sump off anyway. Why not give it a shot while I'm there? What do I have to lose?

If I were to try this, any recommendations on what I should use? Locktite?
Justin

Locktite has numerous formulations, including 2 types of green. One of the green Locktites is a weeping formulation that will "wick" its way into a joint.

My suggestion is to send an e-mail to their tech department for guidence.
Jim Stuart

Let us know what you find out and how it goes as I may have the same problem. Although at the moment it is still silent following its 800 mile (actually two 400 mile) run several weeks ago.
Paul Hunt

I went from shim gasket to composite, didn't notice any difference in performance, but the head oil leak was cured! But the attempt to stop the liner moving from the sump end sounds interesting, and if successful, one to store away for future "retrieval".
Allan

This thread was discussed between 14/07/2008 and 24/07/2008

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