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Bolts on engine block

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Anyone any ideas on this .....

I recently fixed an oil leak from the timing chain cover gasket on my 1965 Herald 1200. When retightening the timing chain cover, I noticed that the bottom bolt was just not tightening and gripping. On removal I discovered that the thread had been completely pulled out.

I had to re-tap the block to a metric 10mm and get another bolt to tightly secure the cover.

All seemed fine and the leak had stopped until today when I drove it I noticed oil was coming around the sump gasket - at the front, just under the pulley, near the above repair site.

I checked the two front sump bolts with a view to 'nipping' them up a bit and discovered that they were loose. when I went to tighten these two, the same thing happened as with the timing chain cover bolt.... ie. it they both just pulled out the threads with no grip !!!

What could be happening. It seems like the block metal at the front has got weak for some reason !!! ????

I've got the sump off now and intend to retap these two aswell and use 10mm bolts.

Any ideas?

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Trouble is if they had made them UNC into the alloy block, 'airy 'rmpit mechanics would be confusing them with the other sump bolts.

That's why I invested in a 5/16 UNF Helicoil kit.

ps Triumph used the same thread in the 2000/2.5 aluminium  rear trailing arms (and they have the same problem).

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The 10mm metric is a common cure (as seen on several of my cars). But DO watch bolt length. I tend to use a sealer as well as OE sump gaskets, they are just SO much better than the repro stuff, but only got 5 left now  :'(

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  • 2 weeks later...

Hi, me again.

Well the 10mm metric bolts worked a treat for securing the sump. However after filling with oil and starting I noticed that the oil leak was infact from between the front engine plate and the block!!!

Looking at the Haynes book, it sems that there is a gasket between the two and I'm wondering whether it's worth a go at replacing this.
So the timing cover, chain and timing wheels would all need to come off to get this plate off. Is it possible to do all this with the engine still in the car?
Has anyone had a go at this?

Maybe I should stop chasing the problem and look for a new engine (?)
Thanks for all your advice.


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