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Cylinder compression issue?


Just Joel

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Bought a 71 510 wagon about a week ago with 103,xxx original miles. Stock motor ran good but leaked from just about everywhere. So I decided to pull it and replace all the gaskets and seals (complete gasket set was only $90 so I figured why not)... Before I pulled it I checked the compression. I tested a consistent 135 psi a crossed all cylinders so after finding this, I figured it was in good shaped and pulled everything out for a re seal. Today, I picked up a service manual I had ordered and read that the motor should be between 155 and 175 psi :( I really don't know a lot about motor work so I'm wondering what others think. Do I have an issue here or am I ok? My current plan involves pulling the head to replace the valve seals/head gasket and inspect the block and head... Is there any tests I can perform then to potentially find the problem if there is one?

 

Thanks

Joel

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your heading in the right direction

 

i would check the cylinder walls, see if there is a lip, might be a good time to have them honed at least, or worst case bored out. New piston rings would be good.

 

I think you can take the head in to have it pressure checked? but your replacing the valve seats so that's good too.

 

im probly missing stuff but im sure others will fill in

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personally if all the cylinders are within 10% of each other and the motor is not burning huge amounts of oil or smoking mad leave it alone and save up to swap motors ot something healthier. The motor you have may be tired but still runs but there is no magic low budget thing to cure age you can just prolong it to buy time.

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Earlier this year I overhauled my L18 (with help from Hainz's excellent vid) on a tight budget - less than R5000 - that's about US$700. Included machining and parts, plus a new radiator. I would fix your leaks and run it - L motors are nice to have!

Edited by zed
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As long as the compressions are reasonably even on all cylinders, it isnt smoking when running then it's fine. I've seen motors with 110 compression and run good. 155-175 would be a new motor. If you already have all the gaskets then go ahead and change them if you want to eliminate oil leaks. BTW you don't have to take the head off to change the valve seals but again, if it's off to change the gasket then that would be the time to do so. The only reason to shave the head is if it's warped and the gasket blew, otherwise save yourself the expense and bother.

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I wouldn't sweat it if it wasn't smoking, using LOTS of oil or making noise. A Krylon rebuild (new gaskets and paint) should be fine. When you did the compression test did you have the throttle plates open or closed? I've seen this make a huge difference in the numbers.

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Yeah, it was warm... I drove it to and from a friends house and tested shortly after getting it in the garage. I don't think it was operating temp but close ;) At this point, I don't feel I want to take this engine any further if I don't absolutely have to. I would rather put the time, energy and money into a L20 platform. I have a feeling this motor will be in the car for at least a couple more years but if it made if forty already, it can certainly go a little longer with a little car.

 

On an unrelated note, looking into the intake and exhaust manifold ports on the head, I can see there is a bit of residue and carbon build up. Considering the fact I

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Deposits are normal even more so for a carbed engine. The fuel mix isn't as well controlled as an EFI car. If you clean it off it will be back in a few thousand miles anyway. You don't have to remove the valves to replace the valve seals nor do you have to remove the head either.

 

Power wash the engine and drive it keeping an eye on the valve cover gasket, around the fuel pump and the front crank seal in the timing cover. These are the 'big three' oil leaks. The fan blows the oil all over so it's hard to locate once everything is wet.

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Yeah, I would but the engine is currently on an engine stand in the shop :P I wanted to clean and paint the engine bay while I was at it so I figured pulling everything was the best option...

 

Given the opportunity, should I clean everything or will I potentially hurt the engine in the process? What would be the best way of doing so if I choose too?

 

Thanks

Joel

Edited by Just Joel
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You can blast that motor with a pressure washer without fear of damaging sensitive ECU stuff - that is one of the many reasons I like my L motor. I spray the motor and engine bay with engine cleaner, leave it a while, then blast it with a Karcher running off a hot water pipe. Just stay away from the distributor and alternator.

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Yeah, I would but the engine is currently on an engine stand in the shop :P I wanted to clean and paint the engine bay while I was at it so I figured pulling everything was the best option...

 

Given the opportunity, should I clean everything or will I potentially hurt the engine in the process? What would be the best way of doing so if I choose too?

 

Thanks

Joel

If you can find it, the best engine degreaser I have found is called Steam and comes in a black can. For the engine bay Simple Green and an assortment of brushes works well. Don't be afraid to post up some pics. We loves the pics.

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Started the evening watching banzai510(hainz)'s vid on L16 break down and built up enough confidence to start work on mine. Everything was going well and I was actually excited to find how clean the top end appeared to be until I found this while adjusting the valves...

 

IMG_1561.jpg

 

It seemed odd at first not to mention the valve was loose as hell. I started digging around to see what was different and found this...

 

IMG_1527.jpg

 

Compared to a complete assembly...

IMG_1528.jpg

 

I'm bummed to say the least... Not only does it seem this motor has been worked on quite a bit, it appears it was all preformed by a moron!

 

Now, I have a few questions...

 

Did this already damage the motor potentially?

 

Where can I find/buy the missing parts?

 

What else could potentially be damaged/warn as a result?

 

While I was taking pictures, I did my best to take some of the valve through the manifold ports... The valve with the issue looks wet to me... how do they look to the rest of you?

 

Exhaust front to back...

IMG_1552.jpg

IMG_1537.jpg

IMG_1538.jpg

 

Intake front to back...

IMG_1548.jpg

The bad rocker

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One of the lash pads fell out, it might be beside the spring or likely found it's way down to the oil pan. No big deal they are easy enough to find and replace. That hear looks OK otherwise. That tan color is normal just keep the oil changed.

 

I would not worry about the bright link unless I was taking the timing cover and chain off the motor. Then it can be located and properly alligned. If you are locking the chain with a wood wedge you should mark the cam sprocket and chain link (anywhere is fine) so that it can be assembled in the same position.

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Good deal... I already checked the head but I'll pull the pan tonight and see if its there... If its not, where can I find a replacement? Is this a common problem? How do the valves look? I'm still considering pulling the head and replacing the valve seals... especially after seeing the "handy work" the last mechanic has done so far I wouldn't mind digging a little deeper for peace of mind.

 

The worst part is that after the lash pad was lost, the person working on the car just adjusted the hell out of the rocker instead of actually fixing the problem :mad: This is why I hate people...

 

Thanks

Joel

Edited by Just Joel
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It's not an unheard of thing to happen. And the previous owner being a moron is also not unheard of:D. That valve guide may have some extra wear due to the missing lash cap. Datzenmike is right - it's probably still in the engine somewhere. I think you may be stressing this more than you need to. Since you plan to just run this for a year or two, you probably dont need to worry about too much "rebuild" type work. My A12 sat in a field (in the car) with a blown head gasket for 23 years. The cylinders had rust pits in them. I had the head cleaned and checked. Honed and re-ringed it and resealed and painted. I ran it for 4 years and had ZERO problems. Sure, it smoked a bit and used a little oil - but it ran like a top every day with very little investment until I got the replacement done and installed. Gaskets, paint, drive.

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Ask anyone here for one, my driveway is covered with them.

 

Do you plan to remove the timing cover? If NOT, the timing chain needs to be 'locked' so that the slack, when the chain is removed from the cam sprocket, doesn't drop down the front and allow the chain tensioner to fall out. Once this happens the only fix is to remove the timing cover an reset the timing chain.

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