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Completed my HG change, simple stuff I've learned...

I've completed my HG change, thanks for the tips to questions in previous posts. I've taken it out for a spin and it's running better than ever, including fixing a long standing irregular idle issue (the very early signs of HG going perhaps?). Thought I might post a few bits and bobs I've learned as a conversion point, mostly to see if others agree or if there are any other suggestions or tips:

- If changing valve stem seals, rebuild the head before taking it for a skim. Sounds obvious, but I didn't know if it could be skimmed with the valves in place. That way you don't have to worry about damaging the freshly skimmed surface putting the valves back in. Putting in my last valve I managed to scratch the matting surface, fortunately is was only around a head bolt hole. The guys who did the skim said it would probably be fine.

- A magnet for taking the collets out would have been handy.

- When fitting and compressing the valves again, most of the time I got a bigger gap at one end of the spring cap. Don't stuff the first collet down there, because it'll be a bugger to get the next collet in. Always fill the side with the smaller gap first.

- When putting valves back in don't cover in copious amounts of oil. When you try and mount the head back on the block, oil will simply pour out of the holes in the head and foul the matting surface.

- Refit the cam when the head is on the car. I found torquing up the head bolts with the cam out is significantly easier and doesn't require any use of extension bars. Plus you can fill each of the valve spring chambers/bearings with oil before fitting the cam follower/shims, without worry of it pouring out. I also found it easier working on the came when the head was securely attached to the engine. Maybe this is easier on a 8v non-interference engine, where TDC is marked on the cam.

- On the Punto you have to remove one of the engine mounts that attaches to the head before you can remove the head. It's well worth reattaching this before attempting to unscrew the head bolts to counter the rotational force. My first head bolt I put some serious twist on the engine with relatively little physical effort by me (I was using a 60cm breaker bar, no doubt significantly increasing the small amount of force I was applying). There's no warning about this in the Haynes manual.

- If you're going to leave your engine supported underneath on bricks for a couple of days (as mentioned above I had to remove an engine mount). Jack up the engine a few cm and support at that level. After I removed the engine mount, about 10 minutes in I noticed the engine was sitting funny. There was a good 2-3cm clearance from the support I had put in. Guess I'd removed the load from that side, so the suspension raised a little. Sounds obvious now.

- This is my personal favourite. No matter how freezing cold, wet and hungry you are, don't just put the head back on the block and torque up if you're not absolutely 100% happy with it. Because next morning you'll be pissed off as f**k with yourself. I did this not once but twice, costing me £30 in new HGs and a new set of bolts.

- After disturbing the cam, finding perfect TDC isn't quite as simple as I thought. If I hadn't marked both the sprockets and the timing belt, I could have easily been a tooth out. I guess this is less of an issue when just doing a timing belt change, as you're less likely to disturb the cam. I guess if I needed to change the timing belt while doing the HG, I'd mark and retain the original. Put this on first to get the teeth aligned and then put on the new belt.

- Always get a head skim. Not sure about this one, seems to be a difference of opinions. But if the car didn't over heat is it likely to require a skim? Seems the general opinion is, if it's off it only costs £20-30 therefore you may as well just in case there are any issues.

- On rare occasions some sections in the Haynes manual tell you to do steps you don't need to do for the task in hand as they cover a more general job. The instructions for dismantling the head instruct you to remove the cam sprocket. I dutifully completed this step, then removed the bearing caps. Only then did I discover that the cam could simply lift straight out and didn't need the sprocket removed. Not a major issue except I was using a bodged tool to hold the sprocket, making the job a bit of a faff.

Regards,

Tim

Reply to
Tim
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Provided the valves don't protrude above the surface being skimmed, you can leave them in place. How exactly did you manage to scratch the surface?

Hammer and suitable socket are easier on 8v engines. Place socket over cap, give it a hit with a hammer, and the collets will pop out. Off course, it's not a good approach for anything with small angled valves, unless the valves are already knackered.

Doesn't make much difference how you do it. Stick the collet in the big gap, then pull the spring compressor/spring/cap across to get the other collet in.

Valves don't need much oil. A quick squirt down the guide before you push the valve in is enough.

Depends on the engine. But it's usually easier to remove as much as you can with the head still attached to the engine, then refit with the bare minimum attached.

Reply to
moray

The magnet lets you grab the collets without putting your fingers near the spring. Bitter experience of pintos has made me think they're a consumable though.

Reply to
Duncan Wood

Pingfuckits win again...

Reply to
PCPaul

They also wear, collets are cheap compared with a dropped valve.

Reply to
Duncan Wood

I didn't expand the spring compressor enough and managed to drag it along the surface of the head. Didn't think anything of it, after all the head is made of metal and I thought it would be more robust. Caused a nice long scratch that went from a hole to the outside edge. Fortunately the hole was for a head bolt and not coolant or oil. I guess coolant would have been the worse of the three to c*ck up on. Not massively expensive to fix I guess, another skim and another £20. But I guess heads only have a couple of skims in them.

I noticed I was reassemble some valves with little effort and other I had to mess with the collets for a while. Eventually I worked out that if you put the collet in the larger gap it would drop down quite far, this would prevent you from creating a big enough gap on the other side of the spring cap to easily fit in another collet. But as the first collet had dropped down well into the spring cap, they could be a pain to shift.

I thought I was being clever at the time. After all I'd cleaned most of the oil off, so lets cover in plenty of oil to reduce ware and tare in the first few seconds after starting. Nope, lets just cover the head and the engine/HG in oil just as you tilt the head a little to mount it back on the car. Lesson learned the messy way I guess.

I ended up doing this three times, due to the fact I put the head back on the car when I wasn't entirely happy with it twice (don't ask, I was just being a knob). First time with the cam on and getting the angular torque gauge to lock around various parts of the cam was a pain. Plus extension bars on an angular torque gauge, with a 3/8" to 1/4" converter makes torquing up that last 90 degrees a little trickier. Much, much easier on the Punto without the cam on, plus less messy.

Regards,

Tim

Reply to
Tim

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