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General Information => Troubleshooting => Topic started by: hipifreq on December 24, 2006, 06:58:39 pm
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The 1.5L in my Dasher had a cracked head gasket that was spitting fire out the number 1 cylinder, so I pulled the head off today. Here's some of the things I've noticed, questions that I'd like to throw out there.
Had a hell of a time pulling one of the head bolts. Some of the bolts were oily, and three were dry. Any reason for the difference or is that normal?
In the space between 3 of valves it looks like there's a tiny crack in the head. Serious problem?
The intake manifold had a small pool of oil inside it under the PCV. I've noticed this before when changing the air filter, but hadn't thought much of it before. Problem?
Valves look good. Plenty of carbon, but they don't have any lateral play when fully open.
I'm thinking of just putting the head back on for now, as I need the car back on the road soon. I'd like to get another engine to replace this one, but that's not for a few months yet. I don't have the tools to pull the valves or replace the camshaft oil seal, so unless I can make/get those fairly inexpensively I'm not pulling the valves.
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I wouldn't worry about the cracks in the head, my bentley manual says if the crack is wider than .02in to replace the head. I don't know why some bolts are oily and some aren't, I have noticed that though. I think the oil in the intake is from blowby, do you have a oil baffle on the cam? If you don't it might help to get one.
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I've had a few engines where some bolts were oily and some were rusty, not sure what causes it.
The cracks are completely normal and as long as they don't enter into the coolant passageways you have nothing to worry about.
If you don't have the cam shield/oil baffle etc on the cam defiantly get one. They are found on all hydrolic lifter heads on vws and gas a diesel ones are the same. No mounting hardware is needed, it sits on top of the cam bolts.
For the cam seal all you need is a 30mm socket (the same one that is needed to remove the axles) Use the socket as a punch. Careful not to knick the metal around the seal though.
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if the bolt has no oil on it, its probably because it is a hot area of the head where the oil evaporates.
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Thanks for the input guys! One of the best Christmas presents one can get is the wisdom of the elders.
Well, since the cracks are pretty small, and I can't find any others visible, I think I'll go to the next step. I'm going to rent a valve spring depresser and pull the valves, then bring the head to a local machine shop to have it shaved just a hair. The head bolts aren't 12-point, they're standard 10 mm hex. Can they be reused? Is it just better to get the 12-point stretch bolts?
#1 cylinder had the crack in the gasket. The little globules seem to be uncombusted biodiesel bits. This is the only cylinder with them.
(http://i121.photobucket.com/albums/o236/hipifreq/No1Valves.jpg)
#2 Cylinder showing the little crack between the valves.
(http://i121.photobucket.com/albums/o236/hipifreq/No2Valves.jpg)
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I don't think you can just upgrade to the 12mm, I think you have to stay with the 10s. I also think that the 10s are reusable but defiantly waif for someone to confirm that. I get that white buildup on my heads and pistons once they have been sitting for a while. I don't run biodiesel so I don't think that's what it is.
That crack looks very, very minor
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Huh, I picked one of the little, white globules up and it slowly melted in my fingers with a scent of biodiesel, so I thought it must be unburned fuel. I wonder if it IS unburned fuel. Not straight fuel, but some biproduct of combustion.
I'm glad to get feedback on the cracks. They REALLY had me worried that I wouldn't be able to reuse the head! This is the first time I've pulled a head, and I don't have someone looking over my shoulder, so everything's VERY new.
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I'm pretty sure your stuck with that style of bolt and I'm almost sure they're reusable, I'm not sure of the torque procedure. My bentley manual is at the shop so I'm going by memory so I'll confirm tomorrow.
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Make sure you bring it to a shop that knows German diesels, you don't want to have your head screwed up by an inexperienced shop
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You may want to concider using Raceware's head studs for the 1.5 TD. The stock strech bolts have a very short thread engagement in the block, even shorter than the 1.6 bolts.
Excuse the plug: http://www.raceware-fasteners.com/photo.htm
I am in no way associated, employed, or hold any interest in Raceware. I just use there stuff in my diesels.
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I've got the Bentley for torquing procedures, but it doesn't say that the bolts aren't reusable. As all the other non-reusable stuff in the book says it must be replaced, I assume these are good to go. I'll certainly clean them up first and apply anti-sieze compound.
There's a good automotive shop in town that the local VW shop brings their stuff too. I'll call to be sure they know diesels well enough.
There was already a 4-notch gasket on there. Will shaving the head require a change in head gasket size? I'll be getting a dial indicator this afternoon, and will check the piston extension for gasket size, but how will changes in the head effect my choice of gasket?
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did vw ever make a diesel motor with non stretch bolts??? i didn't think they did... can't wait to install my head studs though :)
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I don't think shaving the head will effect the HG thickness
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Just install a thinner HG instead of shaving the head. You might wanna measure how far the pistons protrude above the block. I believe the thicker HG is to accommodate higher pistons, though I don't know if the pistons can hit the head with a thin gasket or not. My uncle has a vw shop and he told me they sometimes put a thinner HG on old tired diesels to bump the compression up. I think the 1.5 diesel had non-stretch bolts but I'm not sure. :?
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Well, I just got the head back from the machine shop. Looks beautifull with the shaved head. They took 0.004" off 0.001" at a time, and cost me $45US. Tiny little shop, but they had the setup to do the diesel head. I'm going to start putting it all together today, and will post more pics as I go.
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If you have the time and money, seriously concider the head studs. Either from ATP or Raceware. If i remember correctly, they are 11mm.
The engagement length of the stock bolts in the 1.5 block is really a weak link. There is a real probability of stripping the threads out of the block. The holes in the corners of the block are the ones that will give you heck.
Try putting a bolt through one of the holes in the head and you'll see what I mean. there is alot of unused threads in the block, and the studs can be installed full length in these holes
Good luck
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Thanks for the input on the head bolts. At this point I'm ready to put it all together with the stock bolts. They've been cleaned thoroughly and I'll be tapping the threads in the block before installation. I may have this head gasket in for only 6 months or so before I pull the whole engine to rebuild or maybe get a 1.6na to rebuild for a swap.
I tried using a Dremel on the crankcase surface, and it worked pretty darned well. I used the 280 and 180 grit buffs (attachment 511). Going slow, with not too much pressure I was able to remove the carbon build-up from 3 of the cylinders before the scrubbers had worn away. Had to get more today, and will finish up tomorrow. Here's a look at what the #4 cylinder looks like compared to the others. Unfortunately the glare in the photo doesn't do it justice, it looks better in person.
(http://i121.photobucket.com/albums/o236/hipifreq/Crankcase_partclean.jpg)
Here's a shot of the head after the 0.004" shave it got at the machine shop.
(http://i121.photobucket.com/albums/o236/hipifreq/ShavedHead.jpg)
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I often wondered if it'd be good or bad idea to take such as a dremel and very lightly and carefully grind out the cracks, just down to the base of the crack essentially removing sharp edges and in theory lessing the likelihood of it cracking further.
Thoughts?
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i wouldn't mess with that...
the area between the valve that cracks would be a good candidate for some sort of heat reflective material, because that is essentially what is causing the cracks... thin pieces of aluminum crack under stress a lot easier than thick pieces :wink:
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Understood.
How much meat is there before it cracks into a water jacket or something? Can you weld up such a place before coating it with something?
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Happy New Year!! (gregorian)
Problem with installing a heat reflective coating to the area between the valves is that that valves repeatedly contact the head there. I'd be concerned about how the coating would hold up against the unrelenting stress of valves opening and closing against it.
Got the head on the car yesterday and everything bolted down before the New Years festivities took over, and I couldn't finish it all. I've got to check the pump advance, as it turned over but didn't start the one time I tried it.
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there is pretty much nothing you can really do about the cracks between valves...
i myself would prefer a cast iron head like those on a mercedes... they never have head issues!!!
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IT LIVES!
Got everything all together. Cranked it over and it made the most aweful racket! Sounds of metal on metal were coming from the engine. :(
Checked the timing: check
Checked all nuts and bolts were tight: check
Nothing in the way of moving parts: check
turned over again, fired and started, but still making a crazy scraping noise! AH! :x
Hand-cranked the engine, and heard the noise faintly coming from the alternator. A few of the fins had shiny patches on the edge, and so did the mounting bracket! I took it off and noticed that it was thicker on one side than the other, so I flipped it over.
Fired and stayed going without the noise! Quieter running now, although I'll take it easy on the new head gasket for a bit. Now to figure out the pump timing. I got my dial indicator in there, and I think I'm reading 0.037" at TDC. I feel like it should be reading 0.033" (0.83 mm). The Bentley just mentions loosing the mounting bolts and turning the pump, but no pictures. Anyone have a link to a good pump timing thread? Not much luck on the search.
Scratch that: I found a good thread
http://www.vwdiesel.net/phpBB/viewtopic.php?t=2476&highlight=adjusting+injection+pump+timing
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Just in case
http://vwdiesel.net/phpBB/viewtopic.php?t=5949&highlight=burnyourmoney