Last night I finished putting the Astra back together following a replacement of the head gasket. Job went fine in general other than a few niggly bits and the odd rust welded bolt.
After fitting a new battery it started up fine but sounded a bit tappety. One loud tap overall. Sounds like it could be coming from the top end.
I have read elsewhere that the engines need the valve clearances checked and shims fitted every 20K miles? Could this be whats causing the tapping ?
I will measure the clearances tonight/tomorrow and post them for confirmation.
If they do need shims fitted how easy is this, and what is the basic procedure ? ie - Cam out and timing belt removed etc ?
I have never done this on this engine, but I believe it is not an easy job, you can borrow boxes of various size shims from some garages on the understanding you pay for the one's you use, or Vauxhall will probably sell you a set.
Certainly sounds like it. As for needing the valve clearances reset every 20K, that sounds like cobblers. Given regular oil changes, that seems an absurdly low mileage for shimmed tappets.
I'm not familiar with your engine. Some engines with shim set tappets have the shims on top of the buckets, so the shims can be changed without removing the camshaft. Others fit the shims inside the buckets, which does require the camshaft to be removed. Basically all you do in either case is check all the clearance. Then replace the shims on any that are not correct. If one is say 0.2mm too great, you replace the existing shim, or shims, with shim/s that are 0.2mm thicker. Straightforward enough, but it can be time consuming on a 16 valve engine. After checking and removing all the shims that need replacing, you can work out what shims you need and just buy those. Borrowing a shim set and just paying for those you use is more convenient, but not all garages are prepared to let them out of the shop. Mike.
if the engine was quiet before and you only changed the gasket then you have caused the noise during the rebuild. If you haven't disturbed the valves then valve clearances won't be the problem. Excessively high compression can make awful noises on a diesel (Wrong gasket), likewise over advance. first thing to check is cam and pump timing.
I got the car as a non runner so didn't get to hear the engine before the head gasket change. I marked all the pulleys and all the marks line up as before with the new belt fitted. There didn't appear to be any shims on the valve buckets. I think the shims fit on the top as there are little notches in the side of the buckets and a rim around the edge.
__________ _______\__¦ \_¦ ¦ ¦ ¦ __________¦
Will measure the gaps before taking on the next task of replacing the front wheel bearings. Oh Joy !
If that is indeed the case, resetting the tappet clearances is relatively simple, and can be done with the camshaft in situ. Although you will need a tool to depress the buckets by contact on their outside edge, so the shims can be removed or replaced. Usually it takes the form of a 2 pronged fork, that locates under the camshaft, and is then pushed down to depress the bucket. If you can fabricate something, that's the cheap way. If not you may have buy or borrow the correct tool for the job. Mike.
Indeed, which usually causes poor starting from cold, on these engines...
You indeed need a cam holding tool during which you measure your clearance and calculate what size shims you need for all valves, then pop along to Vx who then sell you the correct ones to pop in. Its not a bad job (1.5hrs) with the proper tools.
Measured the clearances on the engine while it was cold and they were as follows. Taken with valve 1 being nearest the timing belt (left when looking into engine bay).
When I got the car I was also told it needed a set of new bearings and indeed the front sounded awful. However I did note that the anti-roll bar link that connects the roll bar to the wishbone had snapped. As a result the anti-roll bar was rubbing against the drive shaft ! Hopefully this means I don't have to do the bearings !
One thing is certain. The clearances definitely need resetting. :-)
It would help if you also gave which valve is which. Ex or inlet, etc, and what the tappet clearances are supposed to be. I'm not familiar with the 1.7td Izuzu engine, but assuming the valve layout is the typical ex, in, in, ex, ex, in, in, ex. Nos 1, 4, 5, and 8 ezhaust valves should all be the same, as should 2, 3, 6 and 7 inlet valves. If that assumption for the valve layout is correct, the sizes you've measured, suggest to me that the shims, or the buckets complete with shims have have been mixed up and replaced incorrectly. That is assuming the valves have not been removed. OTOH those clearances make perfect sense if the engine has the oddball valve layout of alternate inlet and exhaust valves. Valve seat recession could account for those valves with very little clearance. Without knowing the recommended clearances, I'd guess they should be around
0,2 to 0.3 for both inlet and exhaust, so 4 valves at least have far too little clearance. One further point. Seeing that no valve appear to have a particularly excessive clearance, even with the correct clearances the top end may still be a little noisy if the buckets are slightly loose in their bores due to wear. Nothing to be particularly concerned about at this stage, but worth mentioning, especially if the engine has done a high mileage.
You're probably right. The roll bar rubbing on the driveshaft would certainly sound similar to a knackered wheel bearing. Mike.
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