So Im back, its been a while with no major problems but good fourtunes fade fast. Here is my problem.

I had an exhaust leak due to broken exhaust studs, tried to easy them out but turns out not so easy. tried to oversize the stud by drilling it out and tapping a new larger stud only to drill into a water jacket...... dead head im guessing.

I have another head but its victim to a broken timing belt and has a bent valve. My question is can I swap out the good valves from the dead head into the head with bent valves? I am getting a upper head gasket kit set that I believe comes with valve guide seals, am I barking up the wrong tree? do I have enough material to salvage my VG? I remember you all as the all knowing and trust your opnion..... please share.

 

my only concern would be the valve seat, if it's damaged, then it'll require machining to get a proper seat.
you could also say screw it, swap the good valves over, do some hand lapping, and you might fix it on the cheap.

 

[quote=
you could also say screw it, swap the good valves over, do some hand lapping, and you might fix it on the cheap.[/quote]

Hand lapping???? Are you saying to check the head valve seat for scaring and try to smooth it out by hand if its dammaged? Is it common to find scaring there after a bent valve issue? should I just go to thr JY and find a head without bent valves???

 

by hand, I mean like this:


If you're not too familiar with the process, I recommend spending some time with the youtubes.

 

Every valve on every engine have "broken into" their seats differently so it's not as easy as just putting in new or used valves and that's it (even putting the valve from say cylinder 1 may not seat properly into cylinder 3 or 5). Hand lapping will help the valve sit better into the head, if not perfect.

 

Well from what I read up (and YouTube’d) on valve lapping, valve machining and valve seating I think I might just leave that to the experts. “I aint reel shmart but I can lift heavy stuff”… I mean really, I couldn’t even easy out 4 exhaust studs without wrecking the head…(I did get three out of four tho). Anyways, the spare head that I have now also needs two exhaust studs drilled out and to have the valve seats machined it’s a min of $60.00 here. I do have four cars to choose from at the JY and the heads are $27 each. I can twist a wrench better than I can see a dial caliper…… thanks for the input guys, I will keep you updated as to my progress. And when I’m all finished with this one I have another 89 5 speed in the driveway with a broken timing belt…… when it rains it pours. hahaha

 

which head is bad (radiator side or firewall side)? i can toss you a complete head on the cheep if you cover shipping and my time.

 

DanNY thanks for that offer, I will let you know after I check out our local JY, I generally do pretty good there and they say they have 4 in my year range but we will have to see. BTW it is the radiator side that I need for this one, however like I said I have the 89 in the driveway that broke a timing belt so I might just go grab three heads if they are there and go the head swap way and take my chances. $27 bucks for the JY head isnt that bad, its the $100 for the upper end head gasket kit that hurts.....

 

Well found a used head at the JY, pulled it in the rain, but it also had two broken exhaust studs. Thought I would take a chance and easy out them on a bench at home.....broke two screw exstractors off in the two drilled out studs...WTH .... what am I doing wrong here??? I drilled them out and used the wedge style easy out.... I used PB blast and a lil heat. This just aint my day.......

 

Take that **** to the machine shop .

 

Well I got the holes drilled out again and tapped them out to a 10m, or the same as the exhaust manifold to y pipe studs. I re attached the manifold to the head and it looks like its gonna work just fine. Now I am just waiting on the upper engine gasket set and timing belt kit to put it all back together.

Another question regarding bent valves tho.... When you break a timing belt on these engines your going to hit a valve, I get that. Do you only hit one valve? How many valves are open at one time? If I see a bent valve in one of the heads would that mean the other head was spared?

 

Well I can officially change the name of this thread to “My worst nightmare” …. No really if a mediator can do that that would be great. So you can read from the start of the thread to see where I STARTED. Well I got the front head and exhaust manifold installed and of course decided it would be best to change the timing belt while I was in there (gates kit, $45 on line) I followed instructions advice and this is my third timing belt change so it went smooth. I bled the antifreeze and fired her up, started right up and ran smooth (after a few min of warm up time and CPU adjustments) it sounded fine so went for a test drive, drove well…… for the first 4 blocks. I stopped at a light and went to take off a lil quick and “bang” the timing belt went. I knew right away what it was, but to be sure to screw myself good and proper I gave the key a little twist…. I knew it was the belt in ½ a sec so I stopped. Towed it back home to the shop, tore it down again and found the belt still on but the six or so teeth around the crank shaft were stripped out and melted. Checked the status of the cams…. Front side head cam turns about three inches then is obstructed ….. Bent valve….. I hate my life….. Back to square one….

 

Just to clarify, the timing belt sprocket on the crank had stripped teeth?? Since the belt is rubber, I'm assuming the only way this could happen is if something got dropped down there and wedged between the oil pump lip and crank? Surely you would have noticed stripped teeth when you put the belt on, so what do you think happend?

 

if a foreign object didn't drop in there the alternative is :

2 types of belt tooth shapes on these motors - wrong one installed? ............ alternatively not enough tension on belt?

 

Yep he probably don't know there is the square tooth 60K belt (1900-1993?) and the round tooth belt 100K (1994-2xxx). Hey, I'm a VE guy what do I know about the VG motor.

 

Clarafication.... the crank sproket was un dammaged, the belt was stripped out just around the area where it sits on the CS sproket.

As for the round tooth belt it wasnt that, Ive seen the round tooth belt, we almost converted my friends max over to the round tooth for better life and duribility of the belt. I will post pictures of the belt later, I also took alot of pictures of the whole process to be used for a write up later, I will let you know when they are up on DropShots.com and you can view them there.

As for the "not enough tension on the belt" if anything I would have to say there was TOO much tension. Like I said before I have changed out two other timing belts on other Maxx's in the past with no problems. I followed the instructions on putting tension on the belt and if anything it could have been too tight. When it was running in the shop for about a half an hour or so it had the slight sound of tight belts, I thought it could have been one of the outer belts (alt, PS pump, AC belt) that needed adjustment.
Not too sure where to go from here.?????

 

Guess that its possible you got a dud belt then? (Me? - I don't believe this is common or even likely - one would surely have tons of belt failures coming off the same production line.........................)

You sure you didn't forget that you dropped a bolt/nut/whatever into the belt area, and it was sitting there waiting just for the right moment to get dumped onto the belt?

 

Head job time man.......remove them and drop them off to a professional machine shop!!!!!

 

Here is why you should not drop in a different head - The piston rings wear based on your valve strength and pressure. Dropping a different head or brand new valve will cause excessive pressure that your piston rings cannot handle - therefore it would cause blow-by - massive burning of oil. So unless you are working on a car with less than 100K on a short block, fixing the valve problem or swapping head would be just waste of time.

But if you want to fix it, you can take the valve out using valve spring compressor, then drop in a new valve. Even a brand new valve would not make a perfect seal against a warn head so you would have to grind it to get it to seal perfectly - this is a job that would require some experience so I would just take the head to a machine shop.

 

Yeah!?

 

All, thanks for the feedback, its true the machine shop is the only fix here. If you want to see some pictures that I took during the process you can see them at DropShots.com, log in as Dirty_Maxx and use the password MaddMaxx..... I will be looking into a shop soon where I have done work before and take him 4 broken heads and see if he can produce 2 working heads for min $$$$..... we shall see, I will keep you informed.

PEE-SOUT

 

While partially true, there are so many other factors that have a MUCH larger impact on ring wear like piston to wall clearance, rod ratio, ring type, oil pressure and type, cylinder wall wear, and so on...

Completely False, not an ounce of truth there. Where did you come up with this??

Again, totally false.

The first half of this is true, any valve used or new, paired up with a different seat usually wont fit perfectly. However, a simple lapping job which can be done very easily in just a few minutes per valve is all that is needed.

Just for an extreme example on a VG engine to illustrate my point... I personally replaced both heads on my engine just shy of 140k. The belt didn't break, but actually came off when a loose bolt one of the cam backed out. While I could only see 3 valves in one head that were obviously bent, (only the intake valves) I replaced all the valves in both heads with used ones from an older set of heads I had laying around. I lapped each valve by hand with some valve lapping compound, reused the springs from the lower mileage head, and bolted the heads back on with the used head bolts. I broke the motor in with 9psi of boost, and after about 750miles I changed the oil and turned the boost back up to 17psi. That engine is still in use, in a new car after 30K or so and doesn't burn or leak a drop of oil. Compression numbers are 190 on all cylinders so there is no way you could say those rings are the least bit worn.

dadswieser, if you need any advice on how to fix your heads yourself, let me know. Its really pretty easy, and Im guessing the only reason your belt stripped is a bent valve in the head you didnt replace. It may have had a valve that was only slightly bent, but quickly overheated the valve guide from rubbing and locked up.

 

Maxpwer, thank you for your educated advise on my thread, I aint giving up just yet. I have a donor engine that ran 3 years ago that I’m going to swap out to get this car going. I have done a few swaps in my time but never with an engine that has sat for so long. I do have another set of heads (one with bent valves) that I will be taking apart to try to piece together a good set of heads. I have a machine shop guy that is willing to help me out at a better than fair price…. My plan is to first fix this 1990 GXE auto and then piece together an engine for a 1989 SE 5-speed. I will be looking to bring my questions to the forum and as always sort my way thru the fact vs opinion. My dropshots account is messed up so as for pictures of my progress I will look into another photo storage / sharing website. I will keep you all up to date…… and thanks again.

 

This should be the last post on this thread for me. I finished the engine swap and shes running again. Lots of pictures of the process on flicker. Sad part about it is if you think about what started this all I could have said " hummm, I got a leaky exhaust maniflod gasket on the front head,.... might as well do an engine swap"....


http://www.flickr.com/photos/69535810@N08/6336990679/

you live, you learn, you share. thanks for being here fellas.

 

That's my plan; I have about 5 broken studs. I decided long ago that I'm going to run this engine 'til it dies, then build/swap.
She still acts healthy, no smoking, average fuel economy, no burning oil, etc, with 271k on the odometer.

Only downfall to the plan is the embarrassing putting that it has :/

 

 

I've also got "a few" broken studs.

At this point in time, I'm devoted to living with them!

 

Been a great ride, but now is time to let her go...... (its ok tho, I still have two other Maximas)..... hehehehe


http://spokane.craigslist.org/cto/2699465716.html