92 q45 timing chain setup help

[edfishjr]

Confused about timing chain install...please help!1. Set the engine at TDC and removed the timing chains. 2. Installed the right side chain, guides and tensioner with all timing marks lining up. The camshaft dowels are pointing as shown in the manual. Haven't had to move a thing.3. Manual (for a 93...its the same as 92, isn't it?) says to turn the crank about 120 degrees before installing left side chain.If I do this, I can see that the marks will all line up (the camshaft dowels point correctly already...its the crankgear mark that right now points straight down and needs to be moved 120 deg). Here is my question: If I follow this procedure, won't the camshafts now be 120 degree different from the way the engine was before? I can believe that some teeth have skipped due to the loose chain, maybe one or two, but could the engine have been running, more or less correctly, if it was 120 degrees off?

[DAEDALUS]

The camshafts turn 1/2 as fast as the crankshaft. Thus if you turn the crankshaft 120*, the cams will only rotate 60*. Indeed, the picture in the manual shows the cam marks roughly 60* forward of pointing "upward". Why do you think the chain skipped at all? Once you removed them both, you broke all relationships between the crank and the cams.

[Q45tech]

Each cam tooth is 10 degrees each crank tooth is 20 degrees.One crank tooth or 2 cam teeth is the ragged edge of exhaust valve contact.........especially when the valve/piston expands from heat.

[edfishjr]

Thanks Daedelus and Q45tech, but I still have a worry..I have this idea that once I turned the engine by hand to TDC with tension sides tight, if I left it there, I could swap both chains and, in theory, everthing would be right. My problem is, that's where I am now. All camshafts are in the same position w/r/t the crank that they were with the original chains on. But the manual wants me to turn the crank 120 deg. with only the new right side chain on and then put on the left side chain. It seems to me that this is going to change the relationships. Obviously, I'm missing something somewhere.

[DAEDALUS]

The manual does say to position the cams correctly after turning the crankshaft. Or are you worried you'll hit a valve while turing the crankshaft?

[John Nordling]

I'm still in the middle of the timing chain/guides project myself because I pulled the pan to get the pieces of the right side chain guides that had broken off out of the oil pickup area.

Now I have decided to replace the oil pump because of the possible buildup of sludge since QTECH thinks (and I agree) that with 91,500 miles on a '90, the oil probably wasn't changed as often as it should have been.

This means that I will have to remove the left side chain and guides and reinstall them, so I am interested in finding out if I did it correctly the first time.

I interpreted the installation procedure step 11. on page EM-23 of the "91 manual requiring turning the crank 120 degrees to be necessary when the heads and all of the valve gear have been removed. This re-installation begins with step 1. on page EM-20. Since everything was already in place on my engine, I pulled the old left side chain and guides, then installed the new chain and guides using the silver and gold mating marks as appropriate without turning the crank 120 degrees.

To verify the timing, I kept the left side chain under tension by wedging a socket between the water pump housing and the upper chain guide. This was necessary because otherwise, you have to put the upper left timing cover on to install the actual chain tensioner. On my first try, I was off one tooth on the intake cam sprocket, but it was easy to fix.

I then shared the same fear that you are expressing, so I decided to test my work. Leaving my left "chain tensioner" in place, I carefully turned the crank four full revolutions (e.g., the four cycles) and didn't encounter any resistance other than the tension of the valve springs that you could feel working on the cams. Please note: my spark plugs had been removed too.

Anyone who has done this of course, knows that the timing marks on the left and right chains are no longer lined up! I didn't want to turn the crank in the reverse direction, so I kept turning about 15 minutes (about a third of a revolution each time, which is why it sook so long) and finally everything lined up again. Nothing seemed out of line during this process, so I figured I had done it right.

Now that I am going to pull the left side again, I am hoping someone can answer your question and maybe confirm that the method I used is correct as well.

[DAEDALUS]

I assume that turning the crank allows the chain to be put on with the dowels pointing "up", in a direction parallel to the line of action of the cylinders, and also so that the crankshaft mark is easier to see and not pointing downward. Probably not necessary, just didn't think of it till you asked. Actually, I think the last time I had the cover off I was using an extendable mirror to see the timing marks on the bottom of the crankshaft, so I guess maybe I didn't turn it then either.The marks don't line up after one revolution because the number of links in the chain is not a multiple of the number of teeth on the crank sprocket. I don't think I could turn the crank for 15 minutes...my arm would fall off.

Good job pulling that pan...could you work it out or did you have to raise the engine?

[John Nordling]

So I guess you're saying that this method works! Thanks for the response, DAEDALUS, I followed your directions last fall to replace the chain guides, one thing led to another, and oh, well you know how is goes. Maybe I'll get this thing on the road by spring.

I too used a mirror to check the timing marks on the bottom of the crankshaft. Easy job. I neglected to mention that I set the tension on the left chain by temporarily replacing the upper left timing cover and the old chain tensioner. I squeezed in the socket between the water pump and the upper chain guide as I mentioned earlier, then removed the actual tensioner and the cover. Wanted to be reasonably close to the correct chain tension when I checked the positions of the timing marks.

As for the oil pan, that job calls for patience and perseverance. I followed the shop manual, but it is verrrry light on details! So, I just used common sense. First, I fabricated a left side engine slinger and supported the engine with an engine hoist. This was easy because so much is off of the engine. Then I supported the transmission with an ATV jack, which is a very cost effective transmission jack with about twice the lifting capacity. Cost me $59 plus tax. Finally, I removed the transmission mount and the exhaust system mounts attached in the same area.

About this time I decided I needed to have more room to crawl around under the car, so I put the front of the frame on a pyramid of three railroad ties on each side, using one railroad tie under each of the rear wheels. These things really work well and give you that margin of safety when you're crawling around underneath. (Actually, I use treated highway guard rail posts cut in half.)

Now, I crawled underneath, pulled the sway bar, the steering rack, the tension rods, removed the lower suspension arm from the cross member, tied up wires and hoses, pulled the motor mounts and finally the crossmember. After that, dropping the pan was just a matter of pulling the bolts and a light from a rubber mallet.

Probably more than you wanted to know, but I just don't think there is an easy way for a DIY to pull the pan.

Thanks for listening..........John

[DAEDALUS]

Thanks for the info. I've never done it (still waiting to get a lift in the garage ). I've heard from a former moderator (Infinit tech) that sometimes the pan can be worked out with the crossmember in place, but I think my mounts are sagging way too much to even attempt it. There's no way I'd be able to not smear all the RTV off while I worked the pan back into place.The next time you're under there definitely replace the engine and tranny mounts and exhaust hangers if you haven't already. Too late, I know, but you can get the engine slinger from Joe at Scottsdale for about $8 plus shipping.

[Q45tech]

"but I just don't think there is an easy way for a DIY to pull the pan"

Why we charge $500 as part of a chain guide job [if necessary]and $640 as a standalone......we still probably don't make $100 we would with other jobs consumming the same time.

[John Nordling]

The next time you're under there definitely replace the engine and tranny mounts and exhaust hangers if you haven't already. Too late, I know, but you can get the engine slinger from Joe at Scottsdale for about $8 plus shipping.

I have the new motor and transmission mounts and exhaust hangers ready to put on. Seems that people in NICO give you lots of clues if you read the posts! I wish I had know about the slinger; I may get one anyway.

I'm just waiting to replace the oil pump before putting on the pan so ole fumble fingers here doesn't drop something into the newly installed pan! Still looking for a definitive answer about the oil pump o-rings issue being discussed on another post before I proceed further................John:D

[John Nordling]

"but I just don't think there is an easy way for a DIY to pull the pan"

Why we charge $500 as part of a chain guide job [if necessary]and $640 as a standalone......we still probably don't make $100 we would with other jobs consumming the same time.

Help me out here, Q45tech. I want to pull the oil pump (which as you know means pulling the guides and chains again) BEFORE I replace the pan...........just in case something goes awry. I am still having trouble resolving an o-ring problem before proceeding. Been waiting about two weeks now. Would you please look at the "Q45 Oil Pump O-Rings" post and see if you have an answer?

I owe ya............Johnps After having pulled the pan, $640 looks downright cheap!

[Q45tech]

Never changed an oil pump, looked at a few, measured a few but the o rings always seemed to fit, same response from other techs.

If the oil pump is shot so is the engine ,etc.........if it measures good [psi] it is good. The point is we measure the pressure first and decide. We examine the oil filters for metal and decide.

As it is always less expensive to change the engine than to rebuild one.........to even the condition of a good looking JDM.

We don't even keep oil pumps or o rings in stock........

[John Nordling]

I really appreciate it when members like you, Q45tech, respond even though you have probably heard and commented on the same subject many, many times. It gives us newbies some much needed confidence. One reason I bought a Q45 was because I thought the overhaul of an early 5 liter mercedes all aluminum V-8 engine was probably beyond my expertise. If I get the Q running, I think the Benz will be a piece of cake!

edfishjr came up with the other o-ring part number for the oil pump on that separate post, so I'm good to go this weekend. Scottsdale had them in stock. Before I start, however, I will cut open the oil filter and take a look. Let you know what I find.

ps Any hints about the best way to cut the filter open? If I don't here anything, I'll use a hack saw. I am just concerned about mistaking the metal pieces from the sawing for something filtered out of the engine oil stream.

Thanks again..........John

[gmark]

I'll try to be brief:

I also have done the timing guides on my sons 92 Q45. Now the car won't start. Followed the instuctions and lined up all of the marks. No interference from the valves when we hand spun the engine. It is possible that we let the relationship of the cams on the left and/or right get confused. Car sputters but does not catch when turned over. No backfireing or anything leading me to confirm chain is off the marks.

My questions before I take it all back apart:

Is it possible for the relationship of the cams to be off and still feel no interference? We did a compression test and 150-175 all cylinders.

How can you confirm the relationship of the cams to each other? Stampings, letter or marks on cams?

Very frustrated with this mess and hope someone can help. I'm new to this site and appreciate any help you can give in advance.

Thanks

[Q45tech]

More than 1 tooth will bend the valves. 1 tooth won't stop it from starting.

[Q45tech]

More than 1 tooth will bend the valves. 1 tooth won't stop it from starting.

How did you reset the CAS [ignition timing to ecu] when you pulled that cover off to remove chains?

[gmark]

I'm not sure what your talking about "CAS". Reset CAS is that Cam Angle Sensor? How do I reset them? Thanks

[gmark]

I now know what CAS is. I believe it only goes in only one way, correct. I made sure it was pointing up on the compression stroke for No. 1 cylinder. But when you say reset to ECU that gives me hope. I don't know how or what you mean when you say reset. I've tried adjusting it still no start.

[Q45tech]

You must note and return the CAS to the correct position the upper mounting slot is what allow it to rotate to set the base timing. [Just like a distributer].

If you get it more than 5-10 degrees off [< 1/4"] it may not start.

[gmark]

Ok so if I make slight adjustments to it and then try to start it at some point I will have adjusted it all the way in both directions. If I get A no start then what.

Let me clarify something first. Based on the fact that I line up the links and marks on the cams and don't have any interference and have good compression. Does it sound like I have the cams aligned (in sink with each other) correctly for both heads? Can you confirm that assumption?

Do I need to clear the computer some how? How can I do that?

Thanks

[Q45tech]

The slot is < 3/4" to cover 60 degrees of timming...............start in the middle.

If you hand crank a few times obviously there is no interferrence...........not to say there might not be some when the engine gets warm, however you could have misset opposite from the interferrence direction.

The gear multiplied starter is easily strong enough to bend valves............why you hand turn the system over multiple times while the front cover is off to see that everything returns after 8 complete turns.

[gmark]

Yes I did that. Hand turned the motor until links lined up again. Seemed like more than 8 revolutions.

Lets get back to the cams

2 cams on each side lets take the right side cams. What concerns me is if I got the cams on the right side mixed up since they both have 2 marks on them. Would the valves hit? That to me would be and indication that I've got them correct. My valves don't hit. Is that safe to say.

Same goes for the left side cams. They don't hit.

I'm trying to confirm that I've got this right so I don't have to take this thing back apart. I'm hoping it something else

Thanks for hanging in there with me.

[gmark]

Oh is that 8 complete revolutions of the cams. That makes more sense about 16 revolutions sound good.

[gmark]

Q45Tech:

Oh my god I feel like such an idiot. Last night I got back to the car and checked the CAS again with No.1 clyd on TBC everything looked good (as you suggested). Something poped into my head. Check the fuses, sure enough"injector" fuse blow. Repalced and car started right up. Daaaaaaaaaa.

What a relief the chains/cams are right. I want to thank you for you guidence and support. I'm new to the site and you responed right away to help out someone new. Your site is great and thanks again. My sons is back on the road.......