I am patiently waiting for my cylinder head to come back from the machine shop after having ten bent valves due to an oil pump pulley bolt breaking. This is the 16 valve engine. I have a question for you all. Like some big block or other American made engines, is it a concern to do a valve job and not replace rings or other lower end parts due to compression increase resulting from top work? The engine has 149K and ran very well prior to "the catastrophe". Another question.....Any tips on how to accurately get the additional 60 degrees rotation on the oil pump drive pulley bolt after the required 15 FT/LB? I know this is a critical torque and I want to do it right.

By the way....there was a reader who asked, "how much carbon did you find in the cylinders when you got the head off"? I don't remember your name or address, so hopefully you will get this message. Not much carbon at all. Cylinders in great shape, still shows crosshatch.

Regular followers of the BrickBoard should already know about the oil pump pulley bolt failures on the B234F 16-valve engine. The collective wisdom is that it should be considered a routine replacement item (Volvo p/n 946472) with each timing belt change unless you replace it once and for all with a high strength bolt (metric class 10.9, 10mm, 1.25 thread, 25 mm long, w/flat washer). Seems the standard bolt (class 8.8) may fail due to over-torquing and/or metal fatigue. Also at each belt change, carefully check the oil pump pulley itself for stress cracks, especially where the sides meet the flat on the inside diameter

The spec calls for torquing the oil pump pulley bolt to 15 ft-lbs plus angle torquing a further 60 degrees (roughly 35-40 ft-lbs). I found that carefully lodging a large Allen wrench between the crank pulley, the wrench socket and one of the holes in the oil pump pulley held it quite adequately. You'll want a breaker bar or use a cheater to do the angle torque. You'll also want to use some Loctite blue (mild thread locker).

In addition to the pump pulley, the original style balance shaft tensioner pulley is another known problem area. The original pulley with black plastic teeth and using an Allen head bolt may shed its teeth, especially under extreme (like sub-freezing) operating conditions. The resulting carnage will usually take out the timing belt, damaging the valves. The updated balance shaft tensioner pulley and bolt is p/n 3547543 & 965221. You may need to grind a little bit of plastic off the inside stud in the lower timing cover to get everything to fit.

Just because your B234F has "made it this far without any problems" probably doesn't mean such failures are less likely and Murphy's Law dictates they will happen at the worst possible time and place. If cost is a deterring factor then at least consider the much higher cost of an engine re-build.

Thanks for the feedback Dave. I did read on the brickboard about the pulley bolt and consequently installed a new $1.80 bolt only to undertorque it and spend 900.00 on a valve job. (Murphy's law and I go back a ways) This time around I want to make absolutely sure that I do this properly. Paul, you wrote earlier that this happened to you and you thought that the torque was excessive. Everything I am reading including my factory manual is calling out 15FT/LB + 60 degrees. I still cannot understand the high torque and bolt stretch but I'm not a rocket scientist either. I have purchased a new oil pump drive pulley as the old one has been scored and gouged by the bolt failure. For everyones help, I really appreciate it. Please don't hesitate to keep sending advice. Lord knows, I need it.

Mark

If you have the stock bolt you'll be able to repeat the size and thread to them.

15ft lbs and 60degrees isn't much, btw, especially if you don't know the yield strenth of the bolt. ARP bolts are well known. Also, ARP has some recent experience with Ford 4.6L V8 cam bolt pulley problems.

I'd put in a good ARP bolt, torqued to their recommendation. Since it's a blind hole you can't measure bolt stretch (if you want to confirm the stock bolt yields, measure the stock bolt length with a caliper before you install it and then afterward...if it is .001" or more longer, it has stretched and is for all intents and purpose useless for further use).

Read the arp site...

http://www.arp-bolts.com/

Uncanny! My '91 failed in exactly the same way at around 148K miles. I know of at least one other. Was the oil pump pulley cracked? Do you have the pieces of the bolt? Was there any evidence of a defect? I am wondering if the torque spec is a bit too tight and overstresses the bolt. Do you know if the spec is the same as for the 8-valve oil pump pulley? There's got to be a reason why these fail so regularly.

No concern on not doing rings, cylinders, pistons with the fresh head work. Oil consumption after head work is an urban myth as far as I am concerned.

Ture, that myth comes from a neglected engine which had no oil changes. They replace the head because of worn cam and later find out the damage is worse off. Hence burning oil and moving to heavier oil. A lost case.

Not a problem here with a broken oil pulley.