# Tell me it ain't so!!!



## scout (Aug 24, 2007)

Bought an 89 D21 that had been overheated. Bad burn in head between 3 and 4 cylinders. Replaced the head with a new one from Clearwater heads. Was very careful putting it all back together. Got it cranked yesterday and it would idle once I got the timing almost close, just twisting the distributor. Noticed a lot of blow by coming thru the various hoses back into the throttle body from the valve cover and I assume the bottom of the engine. Not sure of the source but I suspect rings are bad somewhere. Got a compression test done just a few minutes ago, done per the Nissan manual with the exception of the engine not being warm and the battery not maybe up to snuff. But, here are the numbers: (1) 140 psi, (2) 70 psi, (3) 40 psi, (4) 150 psi. Two and three did not change significantly with the addition of oil in either. Book say standard is 173psi, minimun is 131, all should be within plus or minus 14psi.
Manual says two and three may have a bad gasket between them, but wouldn't they have almost identical pressures if there was a leak between them? If I put the plug in either two or three and either one goes up I would be happy. 
I guess I am looking for an answer to a question that I don't even know how to phrase.
I just don't want to have to pull the whole darn thing apart again before I am assured by more knowledgeable people that it is a requirement in order to fix the compression. 
Right now I am going to pull the valve cover off and just watch the valves to make sure they are moving and see if there is a problem there with the new head from the top side.With a little luck maybe I did not adjust the valves correctly.
Help!!!


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## zanegrey (Dec 5, 2005)

did you check to make sure that the block was not warped ??


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## scout (Aug 24, 2007)

no, I didn't but I bet I do this next time when I have to tear it all apart for the second time.


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## scout (Aug 24, 2007)

Further info. Neighbor seems to think all the symptoms point to a timing chain being a tooth or two off. I pulled valve cover and lined up tdc for #1 on compression. Distributor is lined up for #1 plug. I got to looking at the cam sprocket notch hole and wondered if I have the cam aligned up with the correct version of vertical. Is it supposed to be vertical and perpendicular with the floor/top of the radiator or is it supposed to be vertical and perpendicular with the top of the engine head?
I aligned up the tdc mark on the crank for #1 and the notch hole in the cam sprocket is in the vertical position in relation to the floor. If I line up the cam sprocket notch to be vertical and perpendicular to the engine head then the tdc mark on the crank is about 20 degrees ATDC. That translates into about two teeth on the cam assuming 38 teeth. There is an aftermarket cam sprocket on this truck. It has no marks other than a punch mark at about two o'clock from the cam sprocket notch. No other marks as illustrated in the Nissan manual.
I know this isn't rocket science. I have done it on Miatas, Volvos, Toyotas. 
Any suggestions are appreciated.


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## zanegrey (Dec 5, 2005)

many times after doing this job or a timing chain reeplacement ,the oil pump timng is overlooked or just not timed correctly.

did you time the oil pump ??


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## lcdrjoe (Sep 4, 2007)

*Timing oil pump*

What does it sound like or do wrong if you time the oil pump incorrectly?


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## veesix (Jul 18, 2004)

If it was the chain, all the cylinders would have equal results, right?

It looks like #1 and #4 are good, at 140 and 150 psi.


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## rbo1577186 (Jan 16, 2005)

Maybe, maybe not. If one of the valves are just the slightest bit open - there goes your compression. Depends on how tight the timing is. Might not be open enough to bend a valve, just not hold any pressure. If it was only off by one tooth, I wouldn't imagine one tooth would hurt it that much. 

Compression tests don't lie. Something is really wrong.... Either your mechanical timing is off, you have a faulty head, head gasket isn't sealing for some reason, or maybe your block is slightly warped (head gasket not sealing), a cracked block, something along that line.


Heat damage - gotta check the top of the block. You may be able to use a steel rule and lay it across the top of the block (If you have access to a surface plate you can check the integrity of your rule). If you know a machinist they might have something perfectly flat you could use. Use feeler gages/ or a flashlight to check for warpage. Warpage pecs should be in your manual. *This is a half ass way of doing it*, but you don't have to pull the engine and take it to a shop. With this method you'll know if something is way off. I'm assuming you inspected the tops of the pistons carefully. If they're OK, then I would assume the rings are OK too. It might be worth it to pull the engine and let a machine shop check out the block.. I understand where you're coming from and I would want that to be a last resort too.

I don't know what engine you have but with Nissan's KA24E (I think these weren't used until 90) engine there are no timing marks except for the notches on the timing sprockets. The notches on the timing sprockets line up with marked links on the chain. 

"Oil pump timing" shouldn't have anything to do with compression. "Oil pump timing" keeps the mechanical and ignition timing in sync. You're right it's easy to overlook.... ask how I know..... If the "oil pump timing" were off it would just have your ignition timing out of whack. Compression would still be good.

Good luck


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## scout (Aug 24, 2007)

I am pretty sure the oil pump and distributor are timed as per the manual. There is a half shaft on the distributor and a half shaft receptor on the oil pump. They will only fit one way and that is when the distributor is at #1 plug. 
The cam sprocket I have has got just one small indentation at about the 2:30 spot on the sprocket when the cam notch is at vertical. The chain that is installed does have a silver link and I guess, knowing what I know now, that at TDC with the cam notch vetical I should try to get the silver link on the indentation or as close as possible. The Nissan manual shows several marks on the sprocket and says to use the #2 indentation for alignment with the silver link. Since I have only the one mark I assumed it was not OEM and just decided to get TDC and use the cam notch as the vertical point. Which is what the manual shows. 
Now the trick is to move the chain without having the tensioner pop out of place. Tried a little wooden wedge last time and was not successful. Any tips on how to accomplish that trick? Seems simple to do if you use the right gadget. 
Thanks to all for the information provided. Will try to distill it into something that will help me get past this stumbling block. I did discover something useful along the way. The first step in timing chain work or head removal is to remove those blasted radiator brackets that keep poking you in the belly while you work. Same thing for the hood latch.


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## rbo1577186 (Jan 16, 2005)

Remove the tensioner then take the chain off. While removing keep it together the best you can. You may be able to remove one bolt, loosen another and pivot the tensioner with one hand while keeping pressure on the spring with the other. Stuff the spring mechanism back in the best you can(maybe use a vise and a socket ).To retain the spring mechanism you might try a thumbtack, or a piece of a paperclip. Even if the paperclip is on the small side the spring tension should hold it in place until you are ready to pull it back out. 

When you buy a new tensioner they come with a thumbtack looking retainer. I kept mine just in case I ever need it again.


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## scout (Aug 24, 2007)

rbo1577186 said:


> Remove the tensioner then take the chain off. While removing keep it together the best you can. You may be able to remove one bolt, loosen another and pivot the tensioner with one hand while keeping pressure on the spring with the other. Stuff the spring mechanism back in the best you can(maybe use a vise and a socket ).To retain the spring mechanism you might try a thumbtack, or a piece of a paperclip. Even if the paperclip is on the small side the spring tension should hold it in place until you are ready to pull it back out.
> 
> When you buy a new tensioner they come with a thumbtack looking retainer. I kept mine just in case I ever need it again.


I had the tensioner out last time. That was the easiest and best way to work with it. This time I am trying to just move the chain a few teeth without having to remove the faceplate. I saw the little hole in the top of the tensioner for the pin. Very easy to reassemble and reinstall. Now that I know how it works I am trying to devise something that will hold the tensioner in place while I work on the chain without the tensioner popping out. Surely someone has gotten lucky and devised a gizmo that holds it in place. I think a more slender wooden wedge than I used last time might be better. Will drop by Crown Nissan on Wendover today and see if they have any tips to share.
thanks for your suggestions. I am just over in Browns Summit, North of Greensboro.


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## jblakeslee (Nov 30, 2005)

The tensioner I bought had a small pin in it to keep it compressed while installing...I had the same problem with the chain off a link...used a small screwdriver to push the tensioner all the way back in, then put a paperclip in the hole to hold it there while I took it off to move the chain were I wanted it. worked great.


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## scout (Aug 24, 2007)

got the engine disassembled today and moved the cam sprocket one tooth to better align with all the marks. Re gapped the valves with the new position. Engine is without the oil pan, accessories and belts. Throttle body still remains. I had decided to use the battery for a compression test before reassembly but smelled something around the truck that had a faint electrical smell so I disconnectded the battery for a while. When I went to hook it back up for the compression test I got some arcing from the terminals as I tried to reconnect. So I didn't. Question is what would be drawing current at this point? Yes, the lights are off. Is there a smarter/better way to check the compression before buttoning the whole thing back together. Can I reuse the head gasket even though the engine has not been run but a few minutes at most with the current gasket? Or are they a one time tighten down type of item that can not be reused at all?


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## scout (Aug 24, 2007)

Lots of humble pie got eaten today. Lots of "I told you so's". Finally found a way to pressurize the cylinders and do a reverse compression test that would at least give me a clue as to what was wrong. Screwed the compression tester in one plug hole and pumped 120psi shop air in the other with a screw in adapter with the truck in fifth gear. #1 held at 120psi, #2 90, #3 zero, #4 110. Pulled the pistons and of course it was all obivous at that point. Number three was badly scuffed, the others had some scuffing. Part store said .020 was the next size piston if it needed boring. Question to those who know is how much scuffing is really detrimental and is it worth boring out an engine that is not destined for much, if any, work towing or anything but driving around a rural area. My inclination is to hone the cylinders, put new pistons and rings(the old ones have to be replaced) and put it back together. But I would be glad to hear any and all opinions on how much or how little effort and money to sink into what started as a four hundred dollar truck and is now up to almost one thousand before the new pistons. I will measure the scuffing in the cylinders and make sure they are not out of limits but my wallet has its limits also.


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## veesix (Jul 18, 2004)

With a rebuilt engine, the truck would be worth alot more than $400.


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## rbo1577186 (Jan 16, 2005)

I know it's more work but... since you have whole new top/front end....... If the miles are high.... it may be worth it to pull the block and let the machine shop check it out. The walls may be worn enough that factory spec pistons may not work that well. They'll check the integrity of the block, clean out coolant/oil lines, check crank(grind it if needed), fit it for new main bearings(highly recommended if high mileage), and do all the measuring/tell you what you need. It's usually not too expensive. You may find out that the block is ruined and putting in factory spec pistons is a waste of time..... who knows.

And yeah, if everything is OK It will be worth having $1400 wrapped up in a beater you will drive for a very long time.


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## scout (Aug 24, 2007)

funny you should mention all that extra work! Had a freind from Kernersville who is a long time engine builder come over today and look it over. Out the block comes and off to the shop it is headed soon as possible. #3 is scuffed just a little too much. Hadn't planned such a big adventure but sure am learning a lot. Do you know any shops in the Triad area that you would reccomend for this type of work? I think the NAPA store on W Market in Greensboro might be the choice so far. Might as well look at the clutch while I am doing all this. 
Hell, I might even wash and wax it when I get through if I have any money left.
Thanks for the suggestions. Almost like you knew what was coming up next.


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## rbo1577186 (Jan 16, 2005)

Usually your NAPA/Carquest outsource to reputable shops. I think some have their own in house shops. I really couldn't tell you in the Greensboro/High Point area. I'd ask your engine builder for a reference. 


Absolutely do the clutch. They're cheap and you have all that crap out of the way.


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## tomas hayden (Dec 15, 2007)

*this guy told me to tell you..*

scout if you read this before you reassmble your engine.

check you intake manifolds water jacket for leaks into the fuel passages..

i think this is cause of your intial trouble .
and then caused the second issue ..

now your about to do it again and the whole time it was the intake that was cracked..

i hope you read this before it happens again..

good luck


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## ff14007 (Aug 26, 2007)

very good idea, i had this problem before with a mitsubishi motor i was working on, it took forever to figure it all out. but we put on a different intake and all of the sudden it was running better, and it was still a stock intake. its a deff place to look. good luck


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## thezman (Nov 3, 2007)

well if its scuffed bad enough the 2 and 3 cylinders won't hold compression its prolly a moot point to measure them they may be ok over all but the gouges in them will still let the pressure go unless you bore them. i'd say get it bored and have the top surfaced it shouldn't cost that much and then you can do whatever you want with the truck and feel confident its not going to die at any moment never to run again.


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## scout (Aug 24, 2007)

*I have read it.*

thanks for the heads up on the manifold. I will check it. Turns out the previous block was cracked in several places between some of the water jacket passages and the bolt holes. However, I will check closely the intake manifold for cracks and leaks. 



tomas hayden said:


> scout if you read this before you reassmble your engine.
> 
> check you intake manifolds water jacket for leaks into the fuel passages..
> 
> ...


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