2F Intake/Exhaust/Carb vacuum issues (1 Viewer)

[GoldenDad]

I recently took my '86 FJ60 in to have the intake/exhaust combo gasket replaced - typical slap noise on acceleration. The shop also replaced the fuel line filter, the 2 gaskets at the heat riser interface (btwn the intake and exhaust manifolds), the doughnut, the carb insulator gasket and flange gasket. The K&N air cleaner has recently been cleaned and re-oiled. Since the carb was coming off, I had a rebuilt carb put back in it (from Cruiserparts.net).

The truck seems to run OK when I have the throttle down, choke out or am driving, BUT it idles down and cuts off even when fully warmed up if I am not choked or throttling. TWO caveats: It appears SOR sent me a "block off plate" instead of a replacement heat riser plate - Block off being solid steel and replacement is vented (I assume allowing heated exhaust gas to mix with intake air and actuating a thermal switch that is said to lurk in that intake chamber above the heat riser plate, which is now blocked). The guys who currently have it say that they have sprayed carb cleaner (or ether) along each intake port and that shows no gasket seal leak (i.e. doesn't idle up). I am told by two different mechanics that the intake manifold seems solid, no cracks or signs of damage.

Question(s): Would the heat riser block off plate cause the rough idle or is there an underlying vacuum issue that I need to address? If the intake manifold is solid would it be possible that the guys re-routed some of the 1/4 mile of vacuum tubing wrong causing the idle issue?

I need to get this rig back and purring, because warmer trail weather is coming!!!
Thanks for any help you can provide,
Goldendad

 

[klinetime574]

Was the replacement carb the correct one? Looked the same, same functions, etc.?

Also the carb insulator has no gaskets. They are bonded to the surface. Any additional gaskets would be a waste, and IMO a potential vacuum leak. Have they sprayed ether around the carb base?

I can't really answer your question, don't have much experience with the stock exhaust manifold. Wish I did.

Hook a vacuum gauge up to one of the lines and see how much it reads. Needle should be steady. Mine idles at 21 in/vac

 

[Spike Strip]

If the stock heat-riser flap in the exh manifold is not cut or removed, the SOR heat riser block off plate prevents it from opening when warm and directing your exhaust toward the downpipe. In the pic below, you can see, when cold, exhaust is directed up toward the underside of the intake for quicker warm-up. If that flap is blocked, it will heavily restrict exhaust. Not saying this is the case, but I've seen it before. Is the shop familiar with this? Did the shop install it correctly?

Also, is your Idle Control solenoid hooked up correctly? Working ?

 

[GoldenDad]

Was the replacement carb the correct one? Looked the same, same functions, etc.?

Also the carb insulator has no gaskets. They are bonded to the surface. Any additional gaskets would be a waste, and IMO a potential vacuum leak. Have they sprayed ether around the carb base?

I can't really answer your question, don't have much experience with the stock exhaust manifold. Wish I did.

Hook a vacuum gauge up to one of the lines and see how much it reads. Needle should be steady. Mine idles at 21 in/vac

The replacement carb is correct and looked great. I will definitely check out the vacuum lines this weekend. Thanks for the suggestion.

If the stock heat-riser flap in the exh manifold is not cut or removed, the SOR heat riser block off plate prevents it from opening when warm and directing your exhaust toward the downpipe. In the pic below, you can see, when cold, exhaust is directed up toward the underside of the intake for quicker warm-up. If that flap is blocked, it will heavily restrict exhaust. Not saying this is the case, but I've seen it before. Is the shop familiar with this? Did the shop install it correctly?

Also, is your Idle Control solenoid hooked up correctly? Working ?

The blockoff plate SOR sent me shown below to the right of the diagram, which sits over the opening you picture above. To the right is the actual plate that is supposed to be there. I would think the vents serve a particular function and that removing them and the gas communication between exhaust and intake manifolds kills that function. Thoughts? I will definitely check the Control solenoid though. How does one check that it is working correctly??

 

[Spike Strip]

Your pix aren't showing, but the stock plate allows full movement of the heat riser flap. As stated above, the purpose of that is to warm the intake quicker. The consequence is sometimes this happens:

SOR sells the plate you got to help prevent that. The original style is still available if you want to replace the flat one.

Search for ICS for more detail on it. Easy way to check is tap together the two halves of the GREEN connector on the carb and listen for a "CLICK" from the ICS in the carb... This MUST be done with the KEY on, ENGINE off.

 

[GoldenDad]

Your pix aren't showing, but the stock plate allows full movement of the heat riser flap. As stated above, the purpose of that is to warm the intake quicker. The consequence is sometimes this happens:

SOR sells the plate you got to help prevent that. The original style is still available if you want to replace the flat one.

Search for ICS for more detail on it. Easy way to check is tap together the two halves of the GREEN connector on the carb and listen for a "CLICK" from the ICS in the carb... This MUST be done with the KEY on, ENGINE off.

Thanks Spike Strip! So the SOR unvented plate cannot be causing the idle issue I am having after it is fully warmed up, correct? It sounds more like a seal or vacuum tube issue. I will check the ICS tonight. The picures are very helpful. Not sure what happened to mine.

 

[LAMBCRUSHER]

the sor plate can't cause any vacuum issues by itself, but if the heat riser flap was pointed toward the intake when the block off plate was installed, then it could have baked a hole thru the base of the intake, which will cause vacuum issues. the smog lines should be chased and verified, the vcvs and vsvs should be verified (chased bad vac signal to a vcv once- took forever to find. the vcv had a rupture on the inside that I could only find by removing and testing). the carb may need to be base-line adjusted or worse ( I'll never get another carb from those guys...) you say the idle drops and even dies with no choke after warm...verify the idle cut solenoid is functioning properly- might even remove it to blast the passage clear of any potential clogs. check the wiring to the solenoid and verify it has 12 volts with the key ON. just FYI, the exhaust gasses don't mix with the intake air except thru the EGR system- the heat riser system simply warms the manifold thus warming the intake charge. via EGR, exhaust gasses are introduced to the intake track in order to dilute the concentration of burnable mix (exhaust gasses being unburnable having already been spent) and has nothing to do with the heat riser. HTH

 

[GoldenDad]

the sor plate can't cause any vacuum issues by itself, but if the heat riser flap was pointed toward the intake when the block off plate was installed, then it could have baked a hole thru the base of the intake, which will cause vacuum issues. the smog lines should be chased and verified, the vcvs and vsvs should be verified (chased bad vac signal to a vcv once- took forever to find. the vcv had a rupture on the inside that I could only find by removing and testing). the carb may need to be base-line adjusted or worse ( I'll never get another carb from those guys...) you say the idle drops and even dies with no choke after warm...verify the idle cut solenoid is functioning properly- might even remove it to blast the passage clear of any potential clogs. check the wiring to the solenoid and verify it has 12 volts with the key ON. just FYI, the exhaust gasses don't mix with the intake air except thru the EGR system- the heat riser system simply warms the manifold thus warming the intake charge. via EGR, exhaust gasses are introduced to the intake track in order to dilute the concentration of burnable mix (exhaust gasses being unburnable having already been spent) and has nothing to do with the heat riser. HTH

Thanks Lambcrusher. I will check the ICS first since Spike Strip also mentioned it. I had a knowledgeable carb guy do a base-line adjust and his opinion was that there is a vacuum leak. Looks like I will start chasing smog lines this weekend. Better get some beers!!! BTW: I drove it this a.m. and noticed for the second time that when I kill the engine it backfires. Not sure what that says beyond that it is not burning efficiently??

 

[LAMBCRUSHER]

sound like a vac leak...turn the idle speed screw out all the way. if the idle speed is set too high, the carb will try to idle from the slow circuit rather than the idle circuit, which will pull in too much idle fuel which could also cause some of your symptoms...these carbs are tricky at first. find some local cruiser guys who can come over and give you some pointers. these rigs work best when you do your own work on them. cost less too

 

[GoldenDad]

Finally, I went through the lines last weekend and found a hole in one, and two that were switched on the carb itself. The ICS works (thanks for the suggstion), but I am going to check the intake seal at the manifold gasket, the carb gasket seal and the junction where the intake and exhaust manifolds come together. Then I will have my carb guy re-tune it. Thanks for all of the feedback Spike Strip & Lambcrusher! That was a big help!!!

 

[LAMBCRUSHER]

don't split the manifolds unless you're going to rebuild them all the way. there is not supposed to be any intake leak possible from the manifolds interface, unless the base of the intake is cracked(visible from above with carb off. the insulator has gaskets bonded to it, so unless someone has tried to scrape them off, they should be good, but good to check for leaks there anyway. manifold gasket is very possible. if that is where it is leaking, then might be a good idea to do a full rebuild on the manifolds, might also be a good move to mill the head surface as well, but then that means you're doing a valve job since you're ther...better get some beers.

 

[GoldenDad]

Beer is in hand! Next project. The life of a Cruiser owner, right?!

 

[NookShneer]

Working thru a desmog on my 83 fj60 and ran into a snag at the manifolds. Here is what I'm dealing with:

The intake looks cracked where mentioned in the previous post. See up close.

I have a spare intake which looks like it's in good shape. No visible cracks.

To top it off either while removing the manifolds or previously. A bolt has sheared off the EGR port on the rear (right side of looking at manifolds)

So I have a few questions.

The obvious choice is to swap the intakes out to the non-cracked one. And then have them resurfaced together.

Wondering what the best repair is for the exhaust ear with sheared bolt (grind and have a machine shop weld on a new stud, or cut off drill out tap and put in a new stud) Either way, I don't have the skills or tools to fabricate that so I'm going to have to find a place to do that or find a bolt on solution.

Which brings us to the question of how easily sourced are the exhaust ears to replace? SOR's web site was pretty ridiculous for what I think is the whole manifold. Can the ear be sourced independently and where?

Lastly, is it even worth replacing the stock manifold vs. going with headers and heat riser (PNW)? I've read that 6into1 headers are junk and tri-y are the way to go. Marks off road is out of the tri-y and no definitive reorder currently.

Dave

 

[hank14]

Do you have to separate the manifolds or are you planning to either way? You can have the aluminum intake welded no problem. If it was me, I'd do that and have the weld shop extract that stud- just start treating it now w/ Seafoam, PB blaster, etc. Treat both of those studs and replace them both at the same time.

I'd stick w/ the stock exhaust manifold if you can't get ahold of one of Mark's headers.

 

[NookShneer]

I'll start hitting them with PB Blaster. Didn't think about having the cracked aluminum welded. Good call.

 

[NookShneer]

Spoke with the guys at Torfab today and got their machine shop of choice. Will take the manifolds to them tomorrow and see about the broken stud and resurfacing. They won't be able to do the welding so that will be another shop.

 

[Chris Cahill]

Nook - I just went through the same process you are doing - complete desmog with manifold job. My $.02:

1. Lambcrusher hit it on the head - think long and hard about splitting the manifolds. My stock heat riser and insulator were in good shape but I was insistent on replacing them with the SOR block off plate. I split the manifolds which was a royal PITA, as the bolts that go into the aluminum intake will almost certainly strip to some extent. If they do strip, you can replace them with through bolts. With lots of PB Blaster over a 3-4 day period I got them out with minimal damage to the threads but it was touch and go. Then I had the manifolds machined flat but the machine shop did not spot face the bolt holes as I asked, and seemed to have machined the manifolds separately because some of the intake flanges were thinner than the exhaust flanges. When installing the manifolds, I had to use some half washers of differing thicknesses on the intake side to compensate. I also had to have a plug welded into the heat riser shaft hole. You can trim the heat riser flap to clear the SOR plate but I decided to just nix it for better exhaust flow and because trimming proved difficult without removing the flap. The flap screws were welded and I pretty much destroyed them trying to remove them.
If I had to do it all over again, I might leave the heat riser (unless stuck or damaged) and not split the manifolds. I am happy with the SOR block off plate now but just be aware of what you are getting into if you do decide to split the manifolds for whatever reason. If you have the manifolds machined flat and are going to split them, do the split first, install the SOR plate and then bolt the manifold assembly to the head (without a gasket) with the bolts that hold the manifolds together still loose. Then tighten the bolts between the manifolds and take the whole assembly to be machined flat (i.e., tell them not to split the manifolds again). Insist that the machine shop also spot face the bolt holes and check to be sure they do. If the manifolds are not warped (check carefully with a straight edge), don't have them machined as very few shops seem to know how to do it correctly.

2. Many people swear by the OEM manifold gasket. However, I have used the Remflex gasket on 2 of my 60's and like it. It calls for a lower torque (25 ft. lbs as I recall) and the instructions say it does not need to be re-torqued once installed. Mine have performed very well when installed per instructions and they are thick enough to compensate for a slight warp or misalignment in the manifolds.

3. While the manifolds are out, you should consider removing the exhaust pipe to cut off the air pipe and have the hole welded shut. Makes for a much cleaner job as opposed to stuffing something in the air line to plug it.

4. Consider installing new manifold bolts. I used the SOR manifold stud kit for all of the bolts except the middle top two. In those I used new OEM bolts. IMO, it makes installation and removal a lot easier since the studs hold the gasket in place.

You will love the desmog - very glad I did it and if you take your time I am sure you will be happy with the results. Highly recommend a Jim C carb rebuild as well, he does great work.

 

[hank14]

Here's where I rebuilt my intake/exhaust, starting around post 21:

https://forum.ih8mud.com/threads/how-to-repair-a-cracked-intake-manifold.288422/page-2

 

[NookShneer]

Thanks for the quick feed back, it is super appreciated.

Looking forward to the rewards of the desmog and just want to make sure it's done correctly. After removing all that stuff it's a wonder the truck would run at all with the condition of most of the parts I removed.

If I could find a reasonably priced tri-y header (SOR $700, MAF $650) I'd go that route as it seams I'm a little out of luck.

Plan right now is to keep the intake and exhaust mates together and resurfaced (I'm assuming it will need it, but will look at it with the shops level to check) I'll still have to have them pull the studs and replace them on the exhaust manifold.

Then to weld the intake manifold crack.

I will be ordering from SOR the manifold stud kit and a new gasket into the down pipe.

I wanted to pull the down pipe off and have the excess pipe from the smog pump cut off and welded shut but to my surprise the PO has a one piece exhaust pipe (manifold to tail pipe is welded in one piece)

Plan is to plug the hose with a bolt and once drivable take it to an exhaust shop to have it cut and welded possibly on the vehicle. Or if not pulled off and then an exhaust joint added.

 

[Chris Cahill]

Sounds like a sound plan! Be sure to order a gasket for the egr exhaust port and an egr block off plate if you don't have it. Also verify that your carb insulator is in good shape and will make a good seal to prevent vacuum leaks there. They are still available new from Toyota.