2004 XC 70 Timing issues

Post by **F250** » 20 Sep 2016, 13:05

OK... I'm in learning mode, now...

Just how do you know when you have the crank at TDC? I assume that since crank is splined that there is a missing spline tooth in one position (and corresponding wide tooth on the pulley) to prevent incorrect alignment?

crankycar · Post by **crankycar** » 20 Sep 2016, 13:38

The spine issue is correct as you said it, I get exactly 1 1/4 turns on crankshaft. From here I am going to advance or retard the crank and see what I can do as fixer said something is out of sync. and tonite I get a bore scope and will see what that shows, this is just weird, I have moved the crank position about 1/2 a tooth and no difference so no it is more extreme, need to nail this down somehow..to see what is going on.

Post by **chrism** » 20 Sep 2016, 14:05

Granted, the crank/cam timing may very well be out of sync, but that's not the primary cause of the BIG issue. If it was, you wouldn't have to rotate the crank 450 degrees before you detect the first occurrence of internal contact. There would be at least five, and possibly ten occurrences of contact within 720 degrees of crank rotation. If ONE cylinder's valve is out of sync, then ALL cylinders would be out of sync by the same amount.

It really sounds like you have something going on within one particular cylinder.

crankycar · Post by **crankycar** » 20 Sep 2016, 15:22

But the crank has to turn 2 full turn to get the valve piston combo to repeat itself, so I am with you it is 1 cyl. that has a hiccup, I moved and found my crank mark is only 1 tooth off of actual TDC (used a dial indicator to check this) be only 1 tooth early or BTDC (not the about 20 degrees some say, I moved the crank to 1 mark (being a additional valley in the sprocket) and crank rotates, at 1.5 marks it just touches, at 2 marks it hits hard, so now I will take it the other way and see if it hits in a similar fashion, as I don't know which way to set it, eg what reference marks to use, if it hit after (turning past mark on crank sprocket) it is a no brainer, but will still check with a bore scope as it should hit on all cyls, being a timing issue, I too feel it is a interference issue on 1 cyl. will let you know, at least I am getting somewhere. thanks

crankycar · Post by **crankycar** » 20 Sep 2016, 20:46

Bore scoped the cyls. look normal and nothing excessive, removed the front balancer and hub nothing stripped there, so together she goes with the timing mark set one tooth early, as that is where I can turn it over, and will see what happens, with tolerances that close wonder ing how the VVTs get there clearance to work, as it seems to me they advance the cams even more, someone understand more on this VVT stuff please chime in. will let you know how it runs tomorrow. wish I knew how to post a pic of the hub and how I timed them.. took pt# off of hub will see if it is the correct one..

Post by **F250** » 21 Sep 2016, 06:58

I'm with you on the seemingly odd issue of clearance in comparison to the amount of inherent VVT hub play. When I had mine out of time and was hitting hard on something while turning by hand, it was only a difference of perhaps 2-3 teeth positions which is well less than the full VVT hub's range of movement. It just didn't seem that it all made sense, but I proceeded (as you are) with resetting the timing in a proper fashion, and the car runs like a top.

On the surface. it still seems like there is some black magic in there somewhere. However, when my engineering brain kicks in, I can also see how the amount of hub variance driven by the ECM is far less than the actual potential movement, and that the remainder of the movement is built into the hub as a potential convenience for having the mechanic make final adjustments without necessarily having to remove the hubs and belt over and over again if there was a sloppy initial re-install.

All I know is that once I got the timing set correctly, she runs great!

crankycar · Post by **crankycar** » 21 Sep 2016, 08:41

There is a 2004 wreck in a yard here, I will go in and see what he wants for it, this has me so in a learning mode, I would do a cut away and see how it all works. I would make some fake cam bearing blocks and do the spin and see test, aaahhh just like when I was a toddler, would do that in the scrap pile that was around Dads shop, we had a saw mill in yard, even went to see how a magnetos worked on visiting neighbor boys, was sick fun though.."hold the spark plug and I will spray this on and see if it fires, it fired all right, many times as it was run by a washing machine elec. motor...but it instilled my desire for the trade I took up..
one more thing, what snake oil would clean the combustion chamber, asked a Mopar mech. about their Combustion Chamber CleanerPT#0VU01788 and he said it felt like stealing from customer, have put Marvel Mystery and acetone, and Eng flush, down the plug holes and blew it around with air to distribute it, will oil the chambers well before firing, as with scoping #4 showed buildup, and then will try retime to Factory hub mark not my will work mark, just cant wrap my head around a bad mark, the other thing is to 90degree and back stuff in the procedure, would that throw something different, doesn't make a lot of sense why that is there to do, after it is run or before removing belt, what are your thoughts, I will reread the steps and see if it makes any sense now after all this..

Post by **chrism** » 21 Sep 2016, 09:27

I'm really surprised that there is such a narrow margin (2 or 3 teeth) between being properly timed and interfering - kinda scary.

Can you imagine all the logic that is invoked by the ECM in determining the amount of cam advance/retard? Engine Speed / engine load / throttle setting / O2 readings / maybe even engine temperature? Who knows what all? Way over my head. Hopefully it all "just works somehow".

Good luck!

Post by **F250** » 21 Sep 2016, 10:27

Just to make sure, again. The true timing mark on the VVT hub is not the upside down "U", but is the tiny single hash line near the edge of the gear ring which is harder to find, but is different than the U. The little mark is placed once the factory has the timing actually set in the proper position, and if the gear ring was ever loosened and repositioned on the hub, it is no longer a good reference point and can be ground off so you can then re-scribe a new mark when you get it back in alignment.

fixer333 · Post by **fixer333** » 21 Sep 2016, 16:26

crankycar wrote:There is a 2004 wreck in a yard here, I will go in and see what he wants for it, this has me so in a learning mode, I would do a cut away and see how it all works. I would make some fake cam bearing blocks and do the spin and see test, aaahhh just like when I was a toddler, would do that in the scrap pile that was around Dads shop, we had a saw mill in yard, even went to see how a magnetos worked on visiting neighbor boys, was sick fun though.."hold the spark plug and I will spray this on and see if it fires, it fired all right, many times as it was run by a washing machine elec. motor...but it instilled my desire for the trade I took up..
one more thing, what snake oil would clean the combustion chamber, asked a Mopar mech. about their Combustion Chamber CleanerPT#0VU01788 and he said it felt like stealing from customer, have put Marvel Mystery and acetone, and Eng flush, down the plug holes and blew it around with air to distribute it, will oil the chambers well before firing, as with scoping #4 showed buildup, and then will try retime to Factory hub mark not my will work mark, just cant wrap my head around a bad mark, the other thing is to 90degree and back stuff in the procedure, would that throw something different, doesn't make a lot of sense why that is there to do, after it is run or before removing belt, what are your thoughts, I will reread the steps and see if it makes any sense now after all this..

All of the cleaners I have seen really are "snake oil" , a light spray of water judiciously added to the intake while running does the same thing, because most of the cleaning action is mechanical , not chemical solvent action. Also if you have so much carbon build up in the heads combustion chamber or the top of the piston that it affects the the way the car runs , you need to pull the head to clean it. Most of the oil / water/ carbon sludge that is created by running cleaner / water through your engine is not burned , it goes into the cat , and I have seen many cats and o2 sensors killed this way( you can pull the cat before though).
I have never seen rings unstuck by use of anything poured into or run through the engine. If you have ever had to remove old stuck rings clean the groves out you will know what I mean. The cracked oil/carbon is like cement. I have done tests where I let pistons soak for weeks/months in / gas / kerosene / marvel/ seafoam and every other solvent I have and it did nothing. The only thing that will make a dent in it is lye. Dilute solutions of lye are used in some automotive degreasers like purple power, but if you leave them long enough to soften the carbon it eats any aluminum it touches.Also be careful that you dont hydrolock one of you cylinders by adding to much liquid, you can easily bend a rod , blow a head gasket when you start it.

2004 XC 70 Timing issues

Re: 2004 XC 70 Timing issues