Wonky performance after head switch - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.
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Wonky performance after head switch by MaxDamage on 17 Nov, 2014 16:55
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Hi guys. First time posting here. I used to read things here from time to time and this place has been a great source of info for my 1.6 Audi 80.
I had the head replaced the other day, and the chaps that rebuilt it didn't really use an indicator to time the pump. I brought it back in, because the performance on the low end was veeery bad, it only went well after the turbo kicked in. One of the guys increased my idle rpm and the diesel amount, but it still doesn't feel like it used to.
Should I increase the diesel, while lowering the rpm back to the "regular" 900? As far as I can hear (no tacho) they're at about 1300 right now. I can switch to first gear with ease when the car is properly rolling, and I wasn't able to before. It used to run pretty good, even if a bit louder than usual, and I was able to outrun a lot of more 'powerful' cars. I don't think I would be able to now.
Another thing that I'll get back to the shop about. When the car warms up properly, to about 70 to 90 degrees C, when I let off the throttle, the oil pressure indicator lights up and starts flashing rapidly, apparently in unison with the engine RPM. When I took out the oil stick the first morning after (the day before) there was oil well above the grooved area. They said it's not a cause for concern, but I'm not so sure. -
#1 by 745 turbogreasel on 17 Nov, 2014 17:18
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Why did you change the head if it ran well?
What do they claim they did do?
Can you confirm they did any of the above? -
#2 by vanbcguy on 17 Nov, 2014 17:25
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The shop you're using has no idea how to work on a VW diesel...
Any shop doing anything affecting the timing which does not use a dial gauge is bad news. You CAN time these engines by ear but it requires a lot of guess and test plus a very well tuned ear. A shop shouldn't be messing around.
First order of business will be to sort out the oil pressure issue. Start with some sort of gauge even just to check the idle pressure. There are a lot of possible causes - you could have a legitimate pressure issue or they could have buggered the wiring to the sensors. You'll need a gauge to know for sure.
Next you'll need to get the timing set properly. I bought my dial indicator and adapter for about $45 off of eBay - if you are going to own one of these engines for any significant amount of time then it's a worthy investment.
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#3 by MaxDamage on 17 Nov, 2014 18:43
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It ran well until I accidentally overheated it. Who knew the flashing temperature indicator with the needle at normal temp meant that coolant level was low... The old head was cracked between the valves too, so that's bad news. I found a used one for $40 which turned out to be great.
When I took her into the shop for throwing coolant out, they diagnosed it's either a broken gasket or a cracked head. They took it to be x-rayed and it turns out it's cracked, leaking engine compression in the cooling system. This was also evidenced by the water hoses becoming rock hard when you turn the car on. This has been fixed.
@vanbcguy, the oil pressure seems to be 'very low' once the car starts up, with the oil light staying on for about 1-2 seconds after the engine starts. After it goes off, it does not come back on until the engine is at operating temp.
Now come to think of it, it did it before the head switch too, but only once, so I didn't pay too much attention to it. Could it be that my oil pump needs to be replaced?
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#4 by RabbitJockey on 17 Nov, 2014 19:53
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i think you need to find a shop that knows how to work on a vw diesel. you're in the uk? what year is your car?
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#5 by MaxDamage on 17 Nov, 2014 20:11
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Not in the UK. Bulgaria, Eastern Europe. My car is a 1988 Audi B3.
I know this place where they work on diesels, but my budget is very limited at the moment. That's why I'm looking for a kind of a diy solution.
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#6 by RabbitJockey on 18 Nov, 2014 06:46
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we can do that, do you have your own dial gauge and some way to lock the cam?
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#7 by vanbcguy on 18 Nov, 2014 09:00
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It ran well until I accidentally overheated it. Who knew the flashing temperature indicator with the needle at normal temp meant that coolant level was low... The old head was cracked between the valves too, so that's bad news. I found a used one for $40 which turned out to be great.
When I took her into the shop for throwing coolant out, they diagnosed it's either a broken gasket or a cracked head. They took it to be x-rayed and it turns out it's cracked, leaking engine compression in the cooling system. This was also evidenced by the water hoses becoming rock hard when you turn the car on. This has been fixed.
Almost ALL the IDI heads are cracked between the valves, it is totally normal and not a problem as long as the crack is not too big. Over here they say "thinner than a dime" which is a 10c coin, not sure what the equivalent would be there. However it does sound like your head was beyond saving.@vanbcguy, the oil pressure seems to be 'very low' once the car starts up, with the oil light staying on for about 1-2 seconds after the engine starts. After it goes off, it does not come back on until the engine is at operating temp.
Now come to think of it, it did it before the head switch too, but only once, so I didn't pay too much attention to it. Could it be that my oil pump needs to be replaced?
Going by the oil light alone isn't really much of a signal of anything. The oil pressure warning system is really a warning system - it only kicks in when things have gone horribly wrong. It shouldn't be relied upon to verify correct operation, you NEED to get a gauge of some sort. Otherwise we don't know if we are chasing problems with the warning system or with the oil pressure!
I used a grease gun hose attached to an old 150PSI gauge connected to the oil pressure port on the side of the head to verify I had things right on my engine during my build, it worked great. All told it was about $5 worth of parts but only suitable for diagnostics with the hood open.
It is EXTREMELY unlikely that the problem is in any way related to the oil pump. They rarely if ever fail on VWs unless they've been fed sand or something. -
#8 by MaxDamage on 18 Nov, 2014 15:25
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we can do that, do you have your own dial gauge and some way to lock the cam?
I don't have a dial gauge, no. I could lock the cam by locking the pump in place, using one of those ratchet wrench ends, can't I? (English isn't my first language, sorry.)
Thanks for the input, vanbcguy. I'll look up where that port is.
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#9 by RabbitJockey on 18 Nov, 2014 17:40
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no, you need to lock the cam on the back side of it above the transmission. there is a slot in the back of the cam and you put a piece of metal in it to hold it flat with the top of the head. pump lock is not really that important.
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#10 by MaxDamage on 18 Nov, 2014 19:10
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It's going to have to wait until I get a gauge, then. There's this old guy who works on diesels nearby. I might go see him until I get all the equipment I need to time it myself.
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#11 by ORCoaster on 18 Nov, 2014 20:52
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Us old guys nearby that work on diesels appreciate the recognition. It isn't the equipment we like to loan it is the experience and teaching we go for.
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#12 by TimpanogosSlim on 18 Nov, 2014 21:17
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It's going to have to wait until I get a gauge, then. There's this old guy who works on diesels nearby. I might go see him until I get all the equipment I need to time it myself.
When buying tools, be aware that there are many dial gauges that have a shank that is too large for the timing adapter.
Flag down the Snap-On truck and buy an adapter from them. The adapter that every dealership uses is not more expensive than the ebay adapter.
See here: https://vw.snapon.com/SpecialToolsDetail.aspx?itemid=29100012
The cam lock can potentially be replaced by a flat file, or a brass hinge, or something. I did the hinge thing and wasn't really happy with it. I borrowed the Snap-On version and it was pretty good, but $46 seems pretty steep:
http://vw.snapon.com/specialtoolsdetail.aspx?itemid=29090005
There are various deep sockets that can double for the IP sprocket lock. You need an object that is 15.35mm-ish in diameter. $10.19 for the official tool isn't terrible but it's just a cylindrical bit of metal. See if you have a socket that fits snug in the IP lock holes.
http://vw.snapon.com/SpecialToolsDetail.aspx?type=Tools&ItemId=29080005
For my next timing adventure, I bought these special tools:
http://www.ebay.com/itm/261610002329
When that goes stale, that's $28 shipped for the cam lock and IP lock from EWK Tools. They appear to be fine quality.
The dial gauge you want will have an 8mm diameter shank in order to fit the timing adapter snugly (required!), the rod thingie that goes in and out should be about 4.5mm diameter, and it should have M2.5x0.45 thread.
I bought this one, and it appears that it will be Good Enough:
http://www.ebay.com/itm/270350075799
Includes an ISO9001 certification, and a graph from the QC department of it's positional error (which is very slight). And no country of origin markings, for $20.
Vince Waldon's site has a great explanation, better than the bentley manual: http://vincewaldon.com/index.php?option=com_content&task=view&id=24&Itemid=28
Once i finally understood what i was doing, I felt like Robert Bentley had really let me down. The instructions in the bentley manual aren't clear at all. It fails to make it clear that there is a substantial dead spot in the retraction of the pump piston and that turning the engine a little past this point is just fine because what you do when you find the dead spot is assure that the dial gauge is locked in the adapter and then rotate the bezel of the dial gauge to zero it out, and then you simply turn the engine back to near as exactly TDC as you can get and see what the needle on the gauge is pointing at, and then, if necessary, adjust the rotation of the injection pump. -
#13 by vanbcguy on 18 Nov, 2014 21:29
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I believe the OP is on a country that probably won't be frequented by a Snap-on truck particularly often... 😉
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#14 by TimpanogosSlim on 18 Nov, 2014 21:34
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I believe the OP is on a country that probably won't be frequented by a Snap-on truck particularly often... 😉
Ah, well, the VW SST numbers are likely the same, just a different vendor where he is.