invader problem

[wildcat 01]

I recently purchased a 1986 invader, I took it out for a test run when I bought it...worked fine. The next time I took it out I blew a timing belt. I replaced the timing belt and now it wont run. I made sure the no1 piston was at tdc on the compression stroke, lined up the accessorie drive gear with its timing mark. The cam had no timing mark on the valve cover, so I took off the cover and made sure both valves were closed. I set the two lobes pointing up at equal distances from the valves. I made sure that my rotor was pointing at no1 plug wire. still wont go. I replaced the cap,points and rotor. The engine will run for a few seconds at around 1200 rpm then it dies, when it dies it pushes a spray of fuel out the carb. I put in a carb kit as well as a new fuel pump hopeing that was part of my problem...no go. When I put in the new timing belt and tried to start it for the first time it backfired pretty hard a couple of times, thought maybe I kissed a valve, done a compression test all four were good. The engine is a volvo aq 125b. Any thoughts or ideas on what I missed would be greatly appreciated.

 

[Northern Eclipse]

Re: invader problem

You may believe you have lined up the timing mark, but sounds like you might be out 180* on the cam, example if your lined up : which is bottem of cam sprocket lined up to top of crank sprocket ( which is correct with a chevy chain) I think your good but if your lined up with cam dot at the top and crank at the top then your 180* out. I think a good manual here is in order, hopefully a volvo guy on the board can verify this info, I'm only trying to give you a possible scenerio has to your problem, good luck and let us know how you make out.

 

[wildcat 01]

Re: invader problem

Thanks for the reply northern eclipse. I thought maybe I was out 180 on the cam, so I flipped it but it runs no differently. I have no timing mark on the valve cover, so I took it off. With my cam in the center and both my valves closed, I have the option to move about 5 teeth either way with both valves still closed. I have tried to move a couple teeth either way from center but to no avail. I have a seloc manual on the volvo but it doesnt go into detail on what to do when you have no cam timing mark. I'm sure this is where my problem is...I dont know where to set it.

 

[Northern Eclipse]

Re: invader problem

hey wildcat check out a post from April02 2004 about volvo timing, theres not loads of info but take a look, also check this web site<br /> http://www.marinemechanic.com/volvo/volvo/1968-1984_fuelnfiring.htm hope you can sort it out. I had one more thought did you pull the distributer? and re-install , there seems to be very little info on these volvo's I wish I knew more,, but I'm more of Ford/Chevy guy.

 

[wildcat 01]

Re: invader problem

I did pull the distributor out of the block to check the weights to make sure they were free. I believe I put it in the right way because the rotor lined up with the no1 plug wire. When I'm at tdc with no1 piston, should the lobe be coming down on the exaust valve or the intake valve? Thanks northern eclipse.

 

[Northern Eclipse]

Re: invader problem

At the point your at now that cylinder should be on compression stroke both valves closed, then piston travels down on power stroke,so next valve to open would be exhaust to evacuate the camber on the next travel up, just remember that crank only has to rotate 90* for piston to travel from tdc to bdc thus 4 stroke engine 90* x 4=360* which is one revolution, should be back on compression stroke both valves closed ignition rotor at No1.

 

[wildcat 01]

Re: invader problem

I went all over it again...looks right to me. She fires but it wont run. I'm wondering if I have a problem elsewhere. My no1 plug is dry, the other three are wet. Could that be part of my problem?

 

[jlshields]

Re: invader problem

Wildcat, you may have bent some valves when the timing belt went.<br />Northern, 90* crank rotation from tdc to bdc? Think about that! Takes 180* rotation. Your equation of 4X90=360 is just multiplication and does not determine the '4' in 4 stroke. A 4 stroke engine crankshaft rotates 2 times to complete a cycle. Intake and compression is one rotation, two strokes. Power and exhaust is the second rotation, two more strokes. If an engine's camshaft timing is out 180* it is still in time since the crank to cam rotation ratio is 2:1.

 

[wildcat 01]

Re: invader problem

Wouldnt a compression test show a bent valve? The four cylinders test around 120 each.

 

[Northern Eclipse]

Re: invader problem

jlshields Your right, I was trying to explain something I see better that tell, I was suggesting to rotate crank at 90* intervals to see were piston and cam are at and which valve is open/closed. but the real problem here is no timing marks, so how would you suggest he finds is mark, he knows where tdc is and has ign. rotor on number 1, but is not sure if valve timing is correct. As far as bent valve goes that motor is suppossed to have valve relief so it shouldn't tag any. Hey wildcat were in Canada do you live?

 

[wildcat 01]

Re: invader problem

I think I'm getting closer with this damn timing. Its a good thing I have more patience than money...If it was the other way around I think I would have used a bomb by now. I'm from cranbrook b.c. Thanks northern

 

[Northern Eclipse]

Re: invader problem

I hear ya, but when you get it done you'll be the best wrench on that boat, all other fixes in the future will be a breeze, wish I had more to offer , but I'm at the point were I would have to be hands on, such as your doing now good luck and let us know when you get her running, I'll watch this post.

 

[wildcat 01]

Re: invader problem

I managed to find a reference on valve timing with no markes. made a huge difference. Got her running now...little bit rough but not bad. She's overheating a little bit, probably my raw water pump. Does it ever end?

 

[Northern Eclipse]

Re: invader problem

Glad to hear your running, I think the impeller for the volvo is a pretty easy fix. I'm about to get my boat out of storage next week, you might hear me crying for help after that, got a big box of new parts to install...

 

[wildcat 01]

Re: invader problem

Thanks for all the help Northern Eclipse...greatly appreciated.

 

[jlshields]

Re: invader problem

wildcat, 'Does it ever end?' Nope! After you get the boat running check your trailer tires and bearings.

 

[wildcat 01]

Re: invader problem

I will do that, thanks jlshields

 

[wildcat 01]

Re: invader problem

Well, I had her running for a while. The damn thing will run all day at around 1200 rpm. As soon as I try to rev it up, it boggs out. You can hear it sucking air through the carb as well as see fuel being dumped into it. I can slowly work it up to a higher rev. I thought maybe I was a tooth out on the cam, so I jumped a tooth either way, made it worse. Any ideas?

 

[Northern Eclipse]

Re: invader problem

sounds as if the ignition is not advancing, when you changed the t-belt, did you install a new tensioner a weak tensioner may have caused the belt to let go in the first place, If the tensioner was not replaced you could still have a sloppy belt causing some cam lag. Did you check your timing with a timing light? as points been replaced and gapped? the key is at least its running long enough to find out, is the motor misfiring or just bogging or both?

 

[wildcat 01]

Re: invader problem

The motor isnt misfiring, just bogging. I have put in new points rotor and cap as well as set them. I havent put in a new tensioner...something I will check. The motor is supposed to idle around 10 degrees I'm over 20 to get it to run, which made me think I was a tooth out.