Help - gotta do valve job

Reply

  #1  
Old 01-23-02, 02:56 PM
Member
Thread Starter
Join Date: Apr 2001
Posts: 52
Help - gotta do valve job

My '87 Nissan pathfinder just busted timing belt - I replaced first one at about 60k, am right at 120k now. Piece of crap belt cost me alot of money and sweat! OK, if feel better now.

Haven't opened it up yet, but am fairly certain I will have to take heads off and do a valve job. I have the repair manual, and I do all the work on it myself. But never done valve job. Any advice I could get that's usually not in the manual would be greatly appreciated. Thanks, Nick
 
Sponsored Links
  #2  
Old 01-23-02, 03:43 PM
Joe_F
Visiting Guest
Posts: n/a
Do the removal and installation of the head yourself, but leave the machine shop work to the pros. Have a machine shop handle the head so they can check for cracks and replace the valves. Special tools are usually required in most cases.
 
  #3  
Old 01-23-02, 06:55 PM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,567
Before you get too carried away, verify that that particular motor either is or isn't a valve-bender aka interference engine, or did you already check that and just not say so, Joe? This should be either yes it is and heads have to come off or no it isn't and you install the new belt and fire it up.
 
  #4  
Old 01-24-02, 02:08 AM
Joe_F
Visiting Guest
Posts: n/a
TowGuy:

He doesn't state which engine he's got (you know that's a pet peeve of mine, lack of info )

In such case, he can go to Gates Rubber Company website and look up his engine on their "Inteference Engine Chart" and see if this winner shows up as interference or not. Knuckles furnished the PDF file once before on here, but it's on their website which is probably www.gatesrubber.com (check it in www.google.com to be sure )

If it is, likely bent valves. There's a 3.0 and a 2.4 in this year Pathfinder as I recall (first year of production).
 
  #5  
Old 01-24-02, 05:11 AM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,567
His use of the phrase "fairly certain" sounded like he hadn't checked and I was surprised you didn't come back with your standard question of "WHICH ENGINE?". LOL.
 
  #6  
Old 01-24-02, 09:24 AM
Joe_F
Visiting Guest
Posts: n/a
Lol. True.

I feel like a broken record, but I see it in all forums.

My buddies Fish over in the small engine areas, Smokey in the small appliances and Jeff have the same quandries .

The more the better .
 
  #7  
Old 01-24-02, 01:52 PM
xiii13
Visiting Guest
Posts: n/a
I agree with Joe. If the head needs any work bring it to a machine shop to check for cracks & warping. I once did a valve job for a friend who couldn't afford to send it to a shop. Big Mistake! There was a crack in the head that you couldn't see. So I ended up putting the heads on twice instead of once. Learned my lesson real fast.
 
  #8  
Old 02-02-02, 01:23 PM
Member
Thread Starter
Join Date: Apr 2001
Posts: 52
Thanks for advice

Sorry for newbie mistakes - '87 Nissan Pathfinder, 4x4,V6 (3.0l); YES listed as bender; and reason not sure bent is that not sure exactly what or how to look. Taken of Rocker arm covers, turned over, and all valves 'seem' to be moving properly, except for one - after valve closes a little space is left between rocker and lifter. I was planning on taking this head off to check. Is taking head off only way to be sure it's bent? If not, what is best way?

another QUESTION: I thought that putting the new belt on would allow me to start engine without putting all back together (timing belt covers, harm balancer, other belts, etc). Turned it over and it did not even sound close to starting. In fact it almost sounded like there was no compression in cylinders or something - very smooth and quiet as it rotated. Is that just 'cause I have all the peripherals off the front? It is getting fuel and spark, why wouldn't it start? thanks again, Nick
 
  #9  
Old 02-02-02, 02:37 PM
mooser1
Visiting Guest
Posts: n/a
the reason for it sounding quiet, like no compression, is exactly that.....valves have been bent and are not sealing to their seats, hence no compression....get out the wrenches again......
 
  #10  
Old 02-02-02, 03:32 PM
Joe_F
Visiting Guest
Posts: n/a
I agree .

When they bend, they bend .

Take the head off and take it to a machine shop and they will install new valves.
 
  #11  
Old 02-03-02, 04:17 PM
Member
Thread Starter
Join Date: Apr 2001
Posts: 52
Heads off!

Thanks for all the info so far guys! I have the heads off and there are two dents, all exactly the same, in each piston. Gee, wonder why didn't have compression!? It just died so quick with so little noise I thought there was no way they would all be bent. Needless to say, getting a valve job, and since so torn apart, thinking about new piston rings, bearings if needed, hone cylinders. Problem is have to take out front differential - pain in the a**! or lift out engine - rent equip.! Haven't decided yet - any advice?

QUESTION: are the dents a problem? Hate to have to replace pistons unless have to. They are all shaped like a crescent moon, not very deep - no cracks that I can see.

Thanks again for all your help. Nick
 
  #12  
Old 02-03-02, 06:00 PM
Joe_F
Visiting Guest
Posts: n/a
Whoa Nelley.

The problem is probably bent valves in the head. I believe the pistons are SUPPOSED to be domed like that .

Send that head to a machine shop for rebuilding and to check for cracks and then install them using new gaskets. Replace your water pump, belts, hoses and any expendable type items that would be tough to access when the truck is all back together.
 
  #13  
Old 02-13-02, 04:08 PM
Member
Thread Starter
Join Date: Apr 2001
Posts: 52
Yep, 'dents' were supposed to be there, but after cleaning off top of pistons, were very small dents on most from valves. Got heads back from machine shop - they said all valves were a little bent. Anyway, heads are back on and am in the finishing stages of putting back together. Decided not to go any deeper - been without car too long already, plus machine shop said that I would have to use chrome rings, which were harder to install and the honing had to be perfect. Besides, this shade tree mechanic is getting beat up in the cold!

Quick question - putting throttle body back on, scraped old 'gasket' off of it, then went to get new one, and no one carried just the gasket, including dealer - they had to sell me a $128 part that I believe has an air heater in it. The gasket that I scraped off was wierd - very thin and very fragile - extremely hard to get off, and came off in little chunks. I am now assuming that I should not have taken it off, but what to do now - should I use gasket material and make my own? If you have run into anything like this please let me know. Will let you know if/when it starts. Thanks, Nick
 
  #14  
Old 02-13-02, 04:32 PM
Joe_F
Visiting Guest
Posts: n/a
Welcome to Nissan's world with parts! Yikes! Another reason I don't own them (besides the fact they are troublesome )

That is an EFE (early fuel evaporation) unit. I believe you'll need the whole unit. It is the heater grid that warms the TBI unit to evaporate the fuel vapors. Get the exploded view from the dealership and see if there are gaskets (called cover stock) on either side of the EFE grid. If not, it's a whole assembly.

The only other option is to see if any parts store sells a TBI unit rebuilding kit for this application. That might net you the gaskets you need.

Good luck and let us know.
 
  #15  
Old 02-13-02, 04:34 PM
mooser1
Visiting Guest
Posts: n/a
the gasket you took off was "baked" from years of heat.....I would make my own or use a thin bead of high temp silicone before paying that kind of money for something you don't need......
 
  #16  
Old 02-13-02, 04:40 PM
Joe_F
Visiting Guest
Posts: n/a
Thumbs down

No deal on the silicone! Use the proper gasket. A vacuum leak will drive you NUTS and cause trouble.

Gaskets seal, silicone only replaces a gasket when there is no provision in the design for one! . Not to mention some silicone could ruin the O2 sensor over time if put in the wrong spots.

Get the proper aftermarket or OE style gasket and run with that.
 
  #17  
Old 02-13-02, 04:53 PM
mooser1
Visiting Guest
Posts: n/a
I'd be willing to bet that the intake manifolds on your personal Pontiac's and the Olds too, if they've ever been removed, have a bead of silicone sealing both front and back of the manifold.....Holley, Edelbrock and other manufacturer's actually supply the silicone with their products......quickest way in the world to insure you'll get a vacuum leak is to use the stock curved plastic gasket pieces that come with a set.......c'mon Joe, don't you ever watch Hot Rod TV?
 
  #18  
Old 02-13-02, 08:13 PM
Joe_F
Visiting Guest
Posts: n/a
Actually, they'd have a Felpro gasket if one is shown for it .

Yes the factory used RTV in some cases. But not on this Nissan. It is either cover stock or a flanged EFE gasket. No sealant required .

If there's a gasket, that does the sealing, not the silicone .

Good for Holley and Edelbrock. . You won't find one of their manifolds on my Pontiacs. Only the stock GM pieces with what Felpro or GM recommends, nothing else .

The 80 project/parts car that someone gave me does have a Holley Street Dominator and a Performance Series 1407 carburetor by Edelbrock. It's a manual choke. Considering it is about 20 degrees here in NYC (I was just working on my grandparent's 89 Cavalier a little while ago), that car would be a bear to start to use as a commuter car.

Add in the Blackjack headers, lack of tailpipes, Flowmaster exhaust and other performance goodies and you have one raw and stiff car. Lol. I still haven't figured out what has been done internally to the motor, but it sounds pretty lopey when it's running .
 
  #19  
Old 02-15-02, 11:28 PM
Member
Thread Starter
Join Date: Apr 2001
Posts: 52
No one shows a gasket for it. That makes absolutely no sense - if anyone ever takes off the throttle body, they have to buy a new "EFE"?! I don't have $130, and even if I did, I refuse to buy from those theiving jackals - I don't see why I can't buy some gasket material and make my own. The old one just looked like a flat piece of gasket material. If you think that's worth a try, is there any special type that I would need for throttle body?
Also, do I need to put everything back on before I attempt to start? Do I need to put alternator belt on, radiator/hoses, etc?
Thanks again for advice. Nick
 
  #20  
Old 02-16-02, 08:00 AM
Joe_F
Visiting Guest
Posts: n/a
You can try some gasket material, it's probably Kaokork or some other non-asbestos equivalent. Just remember it has to seal or you'll get a vacuum leak.

Usually it comes off in one piece, but probably it's so old and original in your case and is degraded. I have seen links to wholesale Nissan parts on the Internet, might want to try www.google.com and put in "discounted Nissan parts". Might get lucky.

Gotta love Nissan, what a joke. As I said, another reason I don't own one and likely never will. A normal carburetor type gasket on any car is probably a 10 dollar item. Even GM EFE heater grids are probably half that price.

Always budget properly (and in fact always overbudget) for repairs. Things are bound to go wrong.

Yes, put everything back if you are confident that you have done it all right. The motor should run with all its parts
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes