Cannot turn over engine after replacing guides on 90 Q45

[slshearer]

Hi,

I have torn my engine down to replace the chain guides, all the old guides were in tact and nothing was broken, ( Good Oil Mobil 1) since 1992 so I guess this saved the parts from wearing, anyway I replaced all the guides and oil pump chain, but now I cannot get the motor to turn over with the crank bolt, it will rotate about 90 degrees to the right but then the crank bolt locks! I can back it up but it will lock again after about 90 degrees counter clockwise, I cannot see anything (bolts) binding where the chains are located where the front cover is removed, Not sure what I did wrong but would sure like some ideas on what I might have done wrong.Appreciate your kind help

Thankshttp://forums.nicoclub.com/zeropost?cmd=newtopic&id=177#zer...d=177#Stewart
Modified by slshearer at 4:59 PM 7/24/2006

[qsiguy]

My first thought is timing/cams out of wack (that's a technical term)---piston hitting valve? Did you have to remove the timing chain(s) to get the new guides in? Having never done a chain guide replacement I'm prob. not the best one to respond to this. Just first! hehe. Anyone else with experience with this job?

[slshearer]

I did not have to remove the chains, I removed the old guides and the 2 tensioners and replaced them with the revised parts, It could be that the chains jumped while I changed the guides, the slack side of the guides seem to take up any chain slack and tighten up as soon as the engine is turned over by the crank bolt, I am not sure how easy it would be for the chains yto jump a tooth on the top of the heads & I am hoping this would not happen by changing the guides only and the oil pump chain. Thanks for your input I am hoping someone can point me in the right direction

Modified by slshearer at 4:52 PM 7/24/2006
Modified by slshearer at 5:23 PM 7/24/2006

[Q45tech]

Pull the valve covers and the upper front covers and check timing.....your description is CLASSICAL TIMING ERROR.

Luckily you caught it before using the starter which is strong enough to bend valves on first try.

[slshearer]

I may not be as lucky as you suggest as I did try to turn the motor over using the key and it locked up so I may have bent the valves, I have tackled a lot of mechanical work in the past but this seems to be a job I should have not attempted, I hope that I did not damage my engine! I appreciate your input and helpThanks
Modified by slshearer at 6:49 PM 7/24/2006

[szh]

Ouch!

Z

[DrewQ45]

I've never done the job as T-3 is nearby and I trusted them more than myself. I do remember the tech immobilizing the chain with a few strategically placed zip ties before pulling off the old guides. I hope you're able to recover without too much expense.

..Drew...

[66mgb]

Well - at least your guides are done! (I know - don't be a smart azz!)

You're probably looking at $3-4k to repair / replace the damage.

I'd say you would be money ahead if you parted it out, since most '90's only bring $2-3k.

I know it's a sick feeling...I've had a similar experience with another vehicle.

[ScottJackson]

That's a genuine bummer. You gotta keep those chains somewhat tight while doing the guide swap. The valve springs will want to snap the cams out of time. I'm a backyard mechanic also and the guide job is about the limits of my ability. In fact, on Jesda's old green Q, I somehow managed to not get the crank bolt tight enough. I smacked the 2.5ft long breaker handle with a hammer more times and a bit harder than I had with my own Q and mine never did have the bolt come loose, but his did. He had low oil pressure for a bit and luckily caught it before any damage was done. I did see a cool idea on here later that involved wrapping the balancer with steel cable and tying that to the frame to hold while tightening the bolt. ANYWAY, now would be the time to cry and punch a few walls if that's your sort of thing. If it were me, I'd take the opportunity to swap in a big domestic V8 and see how much of a hot rod I could make the car. But then again, I'm a big fan of engine swaps and there's no emissions laws here.

[slshearer]

Thanks for all the moral support, I have pulled the right side valve cover off and the everything looks good, it still binds when I turn the engine clockwise, I cannot see any damage to this side so now I will take the drivers side off and see, sure does not look like the chain could have jumped on the top side of the cam gears, must of jumped on the crank I guess, I will let you all know more when we determine what happened and what was the fix, I have owned thhis car since 1992 when I got it with 26000 miles, been a great car and reliable, I will probably fix it since it is in such good condition, still drives and looks like new ( almost new) Thanks for the input!Stewart

[texasoil]

the chains WILL jump timing if you did not use 'zip ties' or safety wire near the heads to keep the chain TIGHT on the cam sprokets. It will not jump on the crank sprocket because the angle of engagement is much steeper and will hold many times the torque before moving up the teeth and slipping. Good luck. Carefully cheeck the cam timing on both heads. Run a leak-down test on each cylinder (comp ressed air in the spark-plug hole,piston at TDC, listen for leaks out intake and exhaust with fingers crossed. A bent valve will definitely leak a lot.