Headgasket replace while engine is warm/hot

[caykroyd]

I'm replacing my headgasket this weekend on my '86 1.6D.  The problem is I need to drive it about an hour away from my house to utilize a 2nd set of helping hands.  Can the work be done while the engine is still hot?  If not, how long do you expect I should wait?  What would be any issues repairing it hot?  Other fixes at the same time are injection pump replace, water pump replace, shaft oil seals. Any issues with those repairs?  I guess we can do some prep work while it's cooling?  What do you think?



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[RunninWild]

The only issues I can think of would be burning your hands/arms. By the time you get to changing the head gasket the engine should be cold anyways.

Personally I would start with the timing belt and then injection pump then change the shaft seals. That should take you 30min to an hour and give the engine a bit of time to cool. I would then drain the oil, and the coolant and probably give the engine a good cleaning with degreaser (or easy off oven cleaner) and warm water. Cleaning it would also help cool it faster and make it more comfortable to work on while keeping your hands clean for when you get to the head gasket. Now that its clean and a comfortable temperature I would start on pulling the head. The water pump is probably one of the last things I would do, or when one of you has access to it and nothing else to do.

Make sure to use a new bolt on the crank pulley if you change the crank seals. Its tty and non-reusable.

[caykroyd]

Thanks for the info... I will take your advice...

1) Engine cleaning at the local DIY carwash today for the big gunk
2) compression test will be first to get a baseline
3) timing belt, etc as you suggest.
4) spot cleaning
5) pull the head.

I hope I don't find evidence of crank seal leak... I am afraid of the torque requirements (and I don't have a new bolt).. so it won't be done this go around for sure. 

Regarding your comment of draining the oil, do I need to do that?  I just changed the oil.  I guess I could go with a fresh start since I replacing so many things, but I didn't plan to change.

[RunninWild]

Cleaning the head surface is going to cause a ton of dirt and grime to go into your oil galleries and then into your oil. Clean the surface as best you can, slide a razor blade at a 45 along the surface to remove the chunky *** then polish it with a 3m cleaning pad. Use lots of brake cleaner. Take one of the old head bolts and cut some slots in the threads with a grinder and use it to chase/clean the threads in the block as best you can. Make sure the bolt holes are as clean as possible and blow them out with compressed air. Do this after the head surface is clean. Also make sure you flush out the oil galleries and coolant galleries with brake cleaner after you have cleaned the head. Its probably best to do that with the water pump off as well. If this is your first head gasket just take your time and get the mating surfaces as clean as humanly possible. Any scratches or bumps that you can feel with a finger nail will most likely give you issues. Some pitting on the block isnt the end of the world depending where it is. You want all the sealing surfaces (around the cylinders, oil and water passages) to be flat and smooth. Also check the head and block with feeler gauges and a machinist straight edge for warping.

[caykroyd]

This is great advice.... I've read my Bentley 5 or more times over in preparation, but the extra details you give are great.  Regarding the oil/water passages, you mention cleaning out the head.  What about the block?  Can I spray brake cleaner through the block passages, too?  Will this not settle in the oil pan?  Water pump off makes sense for the block water passages, but do I have to drop the oil pan or is it expected that brake cleaner and gunk will drain out the oil pan drain hole?

For a machinist's straight edge, all I have is a carpenter's square right now... Will that be sufficient.. If not do they have proper straight edges at big box stores?  I'll check today while picking up the rest of my items.

[RunninWild]

No a square won't work you want something completely flat. If it didn't overheat and the original gasket wasn't leaking it's fairly safe to assume it's flat.

Yes clean out the block as well. Having the drain plug pulled should be enough to get most of the crap out. Just use a lot of brake cleaner and change your oil and filter after 1000 miles or so and it should be good. Doesn't hurt to pull the pan of you want to go that far but it's not necessary.

Don't use the razor blade on the head though, aluminum is very easy to scratch. Avoid testing the head on the gasket surface, and if you have too make sure you have it on cardboard or something soft that won't mark it.

Everything is clean enough when you run paper towel over the gasket surface and it is completely clean. Be sure to give everything a final wipe with brake cleaner and not contaminate the gasket surface with oil from your fingers.

Copper spray gasket sealer works well too. Spray 2 or 3 coats on each side of the gasket allowing 10-15min for it to dry between coats. The last gasket I did this on literally glued the head to the block, I had to use a prybar the separate them!

[caykroyd]

ok.. Thanks for advice.... I will be sure to clean surfaces and protect the head....  I was just reading about driving after head gasket and timing belt.  It was a TDI discussion, but do I have to let the car sit for a length of time before driving off?  I will be working on this 40 miles away and need to get back home hopefully with my newly repaired car.  Is this not going to happen?  Does it need to sit for a while?  I think the TDI suggestion was a minimum of 4 hours.

[RunninWild]

I don't see why you would need to wait. I don't have a ton of experience doing this kind of work but it's a hard gasket, you're not waiting for anything to cure and set, I dont see what would cause it to need to sit.

Plus it's going to take you a while to get everything back together. If you can get the head, exhaust, and belts back on, timed, wp and all your fluids filled in under 2 hours I would be impressed.

[caykroyd]

2 hours!!! Ha.  10 hours later the head is back on.  Will finish today.  Every part removed was caked with veggie oil that leaked from the pump.  Wire brush on a drill and brake cleaner works wonders, but still a ton of work. 

And the water pump.... With A/C it is a pain.  AC bracket needs to be removed completely, then compressor needs to be moved out of the way and suspended with some bailing wire.  Water pump exposed yet?  No way... It is hidden behind another veggie oil caked bracket. 

Rant over..... Another couple hours today and we'll see how she runs!!!!

But the original post is a none issue.  It was easily cooled off before I got to the head.


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[RunninWild]

Yeah it usually takes a lot longer then you think haha. I think it took me about 6 hours to change the head on my aaz in my samurai. The samurai is a bit easier because its at a better working height, there's more room in the engine bay and the belts are facing the bumper, plus I dont have any of those brackets or accessories blocking my water pump.

[caykroyd]

Maybe a silly question... I have 500 miles on my new head gasket.  I need to pull the valve cover because i forgot to put the baffle back in.  I also forgot the do the 1/4 turn head bolt torque procedure when the car first got to operating temp.  Ok.  Now the question.... Can I do that 1/4 turn torque at operating temp AND the 1/4 turn after 1000 miles now?  Does the 1000 mile torque need to be cold or can it also be at operating temp? Maybe I'm overthinking this.


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[ORCoaster]

Surprised you haven't lost this gasket already.  I would certainly pull that cover and get those bolts another 1/4 turn.  Then I would drive it for another 1000 miles and do it again.  I can't remember if the 1000 miler was at warm temp or cold.  I would have to look it up.  But I would just wait on it for now but get the engine warm and then pull the valve cover, tighten that head down and don't forget the splash guard.  That thing is so wonderful, I finally got one for a Christmas present and the blue smoke is all but gone from the tail pipe now. 

[caykroyd]

Shoot.  So to be clear I torque to 35lbs, then 48lbs, then 1/4, then another 1/4 turn.  But i did not do a third 1/4 turn at operating temp.  Are you suggesting that I'm at a big risk to the head gasket? 
Temp is still stable, water is full and bright green.  I am leaking some oil from valve cover though.  Don't see any leaks at the head gasket junction.


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[RunninWild]

You need to torque it to proper specs. Without proper torque specs the expansion and contacting of the head and block from heat cycling the engine can cause the bolts to slightly loosen over time and can lead to the head gasket giving out. Typically head gasket leaks are internal and not visible. It doesn't sound like you have any problems yet. I would finish torquing it and you should be fine.

[ORCoaster]

Pull the valve cover and just do the last 1/4 turn at operating temp to secure your head to the gasket.  So far you are holding it together but the last 1/4 really seals and gives you the confidence you need to have to just keep  driving it for the next 1000 miles.  When you get close or a bit after pull the valve cover again and do that final squeeze turn.  All should be well for the next 140 k miles.  Maybe 300 k although I don't think the belts wear that well to get 300 K.