Tensioner bolt stuck - options?

Hey everyone,

I need a bit of advice.

I took my 2006 Mk1 ( yep, defo a 2006) to my VW main dealer for a cam belt change/ service/ mot.

(This car is fitted from the factory with a VW Polo 1.6i AFX petrol engine)

The lead engineer advised that the tensioner pulley bolt is corroded and there is a 50/50 chance it will break if they attempt to remove it.  "If it breaks, it is an engine out job to repair it. " The cam belt tensioner is deemed in good condition, so based on VW's advice we replaced the cam belt, but left the old tensioner in place. (…for now… is what I'm thinking)

Question:  Has anyone come across a tensioner bolt breaking and is this really an "engine out" problem?

If the engine needs to come out we do the clutch, engine mounts (any other recommendations?) at the same time, but I am a glass half full type of guy, so need some input on the risk assessment and other member's experience here please.

The car will only do 1000 miles in the next year, so I'm probably safe , but do I have any options here or just bite the bullet and risk breaking the bolt/ engine out?

(Adding a pic of the "youngster" and it's even younger (bigger?)  brother to thank you for your time.) 





 

From reading your woes, it sounds like the tensioner bolt is in bad shape. If the pulley is good but bolt is bad then the real issue is the bolt not the pulley, nor the belt. If the bolt snaps off with a good or a bad pulley/belt the result is the same most likely a totaled engine, ie bent valves and possibly piston damage if your timing gets whacked in the process of the tensioner bolt giving out. It sounds to me like either way you need to replace the tensioner bolt. So if it snaps off what's the problem?…… the bottom half of the bolt will be in the engine. So i would say is it 100% an engine out job…….maybe not necessarily, however, if its snapped off way down in the block then yeah you will most likely have to drill it out, and by drill it out i mean take the engine out split the head off and take the block to a machine shop, not with a hand drill. So chances of it breaking off down in the block pretty high, chances of it needing drilled out pretty high, chances of it messing your timing when the bad bolt goes….. pretty high, so either way you are kicking the can down the road if you replace the pulley and keep the bad bolt the risk profile is the same you are just either taking the chance now or pushing it down the road until it snaps off and you HAVE to do it. I would personally chance getting the bolt out. you have a number of ways to reduce the possibility of if breaking off. Getting some good thread creeping oil, proper bolt removal technices or possibly even using one of those induction heaters to heat seized  bolts. I removed and replaced my tensioner bolt on my restoration job specifically because i did not want that coming off after i redid the whole engine.

Also something else to note is the torque for the tensioner bolt is not "that" much so might come out easier than you think. And on top of that its a pretty thick stud. unless its super corroded, i would say that the chances of it breaking are slim. I've never had it happen to me, others may have a different opinion about it, but I've had plenty head bolts snap off and that defo a machine shop job to get the tails left in the block drilled out with a manual mill.

Also if you end up taking the engine out, i would check over your steering rack, check the mounts (rubbers) and check over all your rubber boots etc too, and if its power steering check the hoses etc. the hose that goes in the back of the steering rack is a total mother to get out because there's no space to get a wrench in there. I couldn't do it with the engine in, luckily i was taking the engine out anyway and after i did that i still couldn't get it out, so next step was taking steering rack out, which was coming out anyway, but the point is its a pain…… also same process putting it back in i made sure i put that hose on before I bolted the rack back in place and hooked up to steering column.

Example of induction heater. Solary Magnetic Induction Heater Kit 1000W 110V For Automotive Flameless Heat Induction Heat 1KW Hand Tool - Amazon.com

Thank you Shubbs - agreed, I need to address this and plan for the worst and hope for the best.

Thank you for taking the time to write up a detailed reply - much appreciated.  

You are welcome kwaak! I would defo see what experience others have had with that tensioner bolt. Also did the VW folks where you took it too take any photos or anything to show you what or how bad the condition of the bolt was? Heres a pic of mine. This is part of my tear down photos before I rebuilt the engine. It's a pretty big (thick) bolt. It's not too long of deep in the cylinder head. You prob want to know what the condition of it is. That might make your decision easier.

NOTE: Also in my first post think I mentioned engine out but just looked at my own photo and the tensioner bolt is in the head. So prob not an engine out job but more of a take the head off job and take that to a machine shop if the bolt snaps off down in the threads.

And another thing, the bolt is prob hardened steel maybe the head is aluminum so I think the chance of it snapping off are even less because of that. The stud is prob stronger than the threads in the head. Again touch base with some other folks and see what they think. Others may or may not have had an issue with this particular stud.

Ask the dealers to put 2 nuts on the stud and tighten them together and use the inner nut against the outer nut to see if it comes loose should work also use some penitrating fluid. Just a thought

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If the 2 nut trick doesn't work, then find a man with a welder and weld the nut on as far down as you can. The heat will probably help. Steel bolt in alloy means you get galvanic corrosion so they can be a pig to get out. Avoid using a long bar on it as that will be more likely to shear it. Normal spanner and tap it with a hammer.

That's the problem with taking old cars to main dealers most of them don't know what they are doing with older cars…
Having a look online at your engine it's similar to what's fitted to uk spec cars, the tension bolt is fitted to the head not the engine block so worst case is it's head off, no need to remove the whole engine…

The garage is saying it's 50/50 chance of the snapping and to be honest that's the case with most old bolts fitted to cars more than 10 years old so it could come undone no problem.

Get socking the bolt with Plusgas and it should come undone, loosen a little then do it back up, loosen a little more then do it back up etc….as if you try to undo it in one go then it can lock up and then it sheers off.

Make sure they coat the new bolt with copper grease and it will not corrode in place.

Try and find an good "old school garage"  with mechanics that are used to old cars and not just cars with computer ports which tells them what to do…

The garage does not want to expose themselves to a possible engine out repair because the bolt snapped, because you might not be happy with the extra labour cost of removing the engine or the head to remove the broken bolt , added to the bill.

Any mechanic is going to make that caveat before attempting to remove it for you.

So it's your call really.

I would use heat on it, and say a prayer to the car gods first!!! You could also soak it in penetrating fluid for a few days prior to the attempt.

Eventually the tensioner will wear out and fail, so it needs to be changed at some point.

I had the same experience with spark plugs once, the garage called to say the spark plugs were tight and they were concerned they might strip the threads in the head.

I said fine, well they need to be able to be changed eventually, so go ahead and I'll take it on the chin if they do strip the threads……..

The plugs were changed with no issue.

I've worked in garages for decades, and I've seen jobs which turn sour like this, and the garage has to bear the expense….. I've heard garage owners say that they wish they had given the customer £1000 to take the job elsewhere, as the garage would be better off !!!!

Looking again at your post - the culprit is a seized nut, not a bolt,  if the tensioner is located on the stud, it means a bit of heat on the nut will expand the nut and it'll loosen easy…..

Thank you so much for the responses and the info Shubbs, 0337, Paceman, mark1gls & jazzydog.

I agree, the risk is mine here .  I have the car back with the old tensioner pulley, but a new belt.  I will book this in again and let them have a go at the bolt and report back.

Really appreciate all the tips.   

A lot of times I have found that that bolt gets bent when the drivers side mount is bad.  so you may need just to 1. replace the mount.
2. Slightly Jack the engine with a board under the oil pan, and using a small hammer 4 oz ball peen tap it a few time to beat it back into submission.

Another trick that I have used before is to Remove the Belt off the pulley and heat it with a propane torch a wee bit.

Use a pair of vice grips clamped as tight as you can get them, around the non-threaded part, and again with the small ball peen smack it in the direction you tighten it (yes I said tighten) a couple of times, then smack it in the direction to loosen, usually works well.

And do yourself a favour - find a small independent garage for future repairs / servicing.

 Main dealers mechanics are less skilled and the dealerships over charge.

Plus they are really not interested in us and our cars.