Bent pushrods causes & repair

[nigelwheeler]

A sorry tale with my mk5 2.5L banana...

2 breakdowns due to undetected leak from water pump causing overheating (not so obvious the first time).

I replaced water pump Saturday, and decided to do timing belt at the same time. I didn't much enjoy setting the automatic type tensioner, and seemed to lose tension initially. I also found instructions on loosening fuel pump pulley to get correct belt alignment a bit late, and it didn't start first try. reset the belt and tensioner and all seemed well.

Sunday morning, added some engine flush and ran up ready for an oil change. 5 minutes later heard some terrible clattering and came out to find engine stopped, came up against obstruction turning the crank.

Took head off. Every single one of the pushrods is bent. There doesn't actually seem to be any majorly obvious [e.g. collision, cracking, blown head gasket, piston damage] damage although not had a chance to check for warping or look at the valves yet. Crank is now turning smoothly.

My questions:

- what is the likely cause of the pushrods bending? - I had the crank/cam/pump locked off for the belt, but must admit to removing pins and doing some twiddling pullies to get everything aligned, but then it did run seeming smoothly and the belt/tension seemed ok, so improper cam alignment, or more likely to do with the earlier over-heating, or even the engine flush?

- what should I pay particular attention to in working out what may have been damaged (eg should I examine the cam shaft or bottom end)? and what other jobs/checks/replacements is it worth doing whilst everything is pulled apart?

- where can I find good info on getting the cam alignment / timing all set up properly again?

- where's best to buy parts - the pushrods seem like an ebay item, but some sellers seem to have a bit of a dodgy reputation - will be looking for the pushrods, possibly valves & gaskets inc. head gasket?

- if you can't help with any of that or general advice, then please do feel free just to wish me an awful lot of luck

Thanks in advance...

[MinorMatt]

I'm going to suggest you were turning the tensioner the wrong way to tension it, or you did not apply enough torque to the clamping bolt.

This allowed the timing to slip causing valve to piston contact.

Replace/straighten the rods
Inspect and replace any damaged/stiff rockers.

Reassemble and re-time (turn and pin everything before the rockers go on)

[Chug]

It sounds like the timing belt wasn't tensioned properly or the tensioner wasn't tightened and the timing jumped and the pistons hit the valves, this doesn't usually cause problems save for bent push rods, you can straighten the push rods out, I've straightened several over the years, or buy new, but check the rockers and rocker shaft and pedastals because sometimes they get broken too, once you are happy all push rods etc are ok then it's just a matter of timing pins in and timing it all up again.

EDIT: snap Matt!

[nigelwheeler]

Thanks guys - two people saying basically the same thing on any internet forum counts as consensus in my book

So just try to straighten pushrods in a vice, no particularly fine tolerances to worry about?

Also, stupid question probably, but can I just check, the cam shaft and injection pump only have one full 360 degree rotation?, i.e. if crank is locked to flywheel with cyl 1 at TDC, then pump will be correct when at 11o'clock-ish, cam @ 6 o'clockish, and they can't be "180 degrees out”. (I have ordered book of Haynes so hopefully I can work out from firing order where valves should be once I have that info)

And any recommendations (or avoidances) for gasket set suppliers?

Thanks again.

[dumper]

You can make that 3 the same opinion and when the belt snaps on a di there’s no need to remove the head as it only bends the rods or / and damages the rockers I never had to remove a head on one be the odd one has happened to others.

[Chug]

Yeah just straighten the push rods in a vice until they roll well on a flat surface.

Although the flywheel does turn twice for one revolution of the injection pump and camshaft, as long as the flywheel is locked with cyl 1 at TDC, then the injection pump is correct when pinned at 11o'clock ish, and the cam @ 6 o'clock ish, they won't be 180 degrees out.

Have you actually removed the cylinder head, or just the rocker cover?

[nigelwheeler]

@chug head is off - I couldn't really figure out/didn't have spline socket to split banana anyway, so inlet had to come off to access rocker cover, and exhaust manifold has been off before, so no major headaches and kinda wanted to take a look anyway in view of overheating . Good opportunity to learn some stuff and have a bit of a general clean up - next time it happens I should just be able to fix without removing the head

[MinorMatt]

Just remember to set the valve clearances with the straightened rods fitted...

[nigelwheeler]

Unfortunately the situation is worse than anticipated.

Having straightened put the rods and refitted the head, I went to time the cam, only to find that the sprocket/nut was loose. On further investigation, the sprocket is cracked and the woodruff key and its keyway slot are completely destroyed. Assuming this happened when the engine cam to an undignified halt.

Also I'm assuming that the woodruff key is located in the end of the actual cam shaft, that therefore this needs to be replaced, and it's an engine out job - Haynes refers to only refitting the camshaft with the crankcase inverted, so not so easy to do in the vehicle.

However, I can see that there's a sprocket spacer, and can't directly see a picture of that end of the shaft and the keyway, so I'm hoping there's a small possibility the woodruff key is actually in a separate part to actual the shaft that can be removed engine in - very unlikely I know, but if someone could just confirm this I'll be able to assess how to move forward (or not I suppose).

Thanks again....

[joinerman]

Whereabouts are you based Nigel ?

[nigelwheeler]

I'm in East Devon.

[nigelwheeler]

NOTE/ADMIN: I can't edit above post re camshaft, but thought it would be better to move it to a separate topic as the question is now quite different:

Please post any replies to new topic (apologies for duplicating)
viewtopic.php?f=4&t=218782

[MinorMatt]

Im fairly sure you can pull out and replace the camshaft with the push rods removed and 8 magnets on sticks down the holes and pulled upwards to give clearance.

You will need to drop the sump to get access too I would think