When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 1979 Delta 88 with a 350 Olds built engine Code ‘R’, the engine was rebuilt before I bought it, about 15K miles on rebuild.
I have had an ongoing problem of the intake manifold not sealing against the heads and the engine running lean and I cannot pass a smog test(High NOX).
I verified the problem to near cylinder #5 area by squirting some carb cleaner and then the engine sped up. Also a lesser leak near #6.
This has been identified many many many times before.
The original stock intake was so warped around the EGR area(cylinder #5) that I thought it best to replace it. I found another original stock intake and had it cleaned and magnafluxed, and then milled 0.005 in. to make sure it was true and flat against the heads in 2004.
I have tried stock type turkey tray gaskets, SCE composite gaskets, I have tried copper coat spray, Permatex Permashield, JB weld, Form a Gasket #1, Aviation Permatex, around the intake ports, etc etc. I checked to make sure the bolts were not bottoming out. Threads cleaned out. oiled...
I cleanup all the surfaces on the intake and head, squeaky clean, no residue or left over gasket. All new gaskets, sealers very time..
I check the intake bolt torque many times after assembly and also after some heat cycles. I then pass smog easily. All parameters are normal.
I have to smog this car every two years and before I smog test it, I re-torque (40 lbs) the intake bolts. I do not see much movement and I do it when the engine is warm.
Then it fails smog as it is too lean, the same intake leak in the same area, I redo the intake gasket again and it is good again and passes smog.
I have done this at least 8 times over the past 16 years and the same thing happens again and again.
I do not put on a lot of miles on this car. Mostly to car shows.
I am looking for a permanent solution. Looking for advice.
I have been using one gasket in all previous times.
Should I double gasket it?
Remember I’ve tried the Turkey tray, Composite, etc etc. gaskets over the years, same issue occurs.
I’d like specific advice on what to try next.
I’d like recommendations on Gasket brand and number, Sealer brand and number for the intake ports.
I’d like specific application steps. Even follow up steps even weeks, months, years later on what to do.
Yes I know the machining my be off during the rebuild but I am not going to put the money into it to redo it. Engine runs great otherwise, it's just the smog lean thing..
I’m at my wits end…….
Thanks,
Fred
Last edited by FStanley; Nov 30, 2020 at 06:28 PM.
What does the gasket look like after teardown? Is the gasket compressed evenly, especially in the area of leak?
About the only thing I can think of is some severe misalignment. Have the heads been milled before?
Unless someone has a better suggestion, I’d run a bead of silicone around every intake and coolant passage, on both sides of the gasket. Unless the machine was off enough to measure with a yardstick, that should seal anything.
What does the gasket look like after teardown? Is the gasket compressed evenly, especially in the area of leak?
About the only thing I can think of is some severe misalignment. Have the heads been milled before?
Unless someone has a better suggestion, I’d run a bead of silicone around every intake and coolant passage, on both sides of the gasket. Unless the machine was off enough to measure with a yardstick, that should seal anything.
Just wondering if anyone has tried this? also what brand and type of silicone??
Any other better sealants?? people have used?? Gasgacnich? Seal-all??
You're work has been thorough and meticulous. Couple of ideas...a long shot...does the engine run warmer than it should? Is it equipped with a light or gauge?
On reinstall, consider new fasteners such as ARP and Loctite on them.
Don't use double gaskets or double turkey trays. Are you using the included end seals for the lifter valley? Folks often ditch those and use Permatex Right Stuff gasket maker to seal the ends of the lifter valley.
I use blue RTV to seal the coolant ports and red RTV to seal the exhaust cross-over. Don't bother with metal block-offs or metal slugs to seal the exhaust cross-over. It just makes it more difficult to seal the intake gasket.
I also think this thread is interesting, but I'm sure it is very frustrating for you! I have never heard of this happening on a Olds V8. Back in the day my wife and I owned quite a few EGR equipped Olds, and as a mechanic in the Lansing Mi area I worked on lots of them. Of course the cars were only 10 yrs old not 40, but still... I wonder if the problem comes from the high temps around the center exhaust crossover and the EGR? Would it automatically cause you to fail your emissions inspection if you plugged the exhaust crossover and EGR? Would you be able to use a pre EGR manifold ( say a 1971) and block the exhaust crossover and use a electric choke on your quadrajet? Or would they immediately say " This car is supposed to have a EGR and it doesn't!", and fail you?? I just thought about a type of engine sealant that was made to seal up the intake manifold corners on some of the 80's and 90's GM V-6's that had corroded because of the different corrosion/erosion problems they had back then with cast iron heads and aluminum intakes, I used some once on a 2.8 S-10 one time with a corroded intake and it worked great. I'll bet they still make it. Unfortunately I can't remember what it was called, but i think it was made by Felpro. Maybe that would help also. Good luck with it Fred, keep us updated!
Would you be able to use a pre EGR manifold ( say a 1971) and block the exhaust crossover and use a electric choke on your quadrajet? Or would they immediately say " This car is supposed to have a EGR and it doesn't!", and fail you??
Yep I live in California. They even tightened up the specs a few years ago. Engine only has 15K m on it. so like new. I think the real problem is that the engine and/or heads were milled wrong and crushes the gasket at the bottom of the port and the top does not have enough crush to seal properly.. I'll be posting some photos in a bit..
Assuming the heads were milled straight, and the intake surface is still 90* to the deck surface, I would think you could fix this with a different manifold and careful machining.
When you have the engine apart and everything cleaned up, set the manifold con the engine without gaskets. Use a feeler gauge to find out how much of a gap you have between all the sealing surfaces. Hopefully things are fairly even, and not excessive.
My other idea, carefully and throughly tape off every sealing surface of the engine. Get a roll of gasket material and glue it to the heads. Embed some small fishing sinkers or some other kind of soft metal in the gasket. Install the bolts, torque to the spec, then remove the manifold. The sinkers will have flattened out under the manifold. You could then measure each sinker and know if the gasket crush is uneven.
If the crush is less than it needs to be, you either need thicker gaskets, remove the heads and mill them, or find another intake that hasn’t been machined.
I think I would try making gaskets with the thickest material you can find. Unless the manifold was machined by Stevie Wonder with a belt sander, I would think some thick material would seal things up
I forgot I double gasketed it the last time... 1st turkey tray gasket, then SCE composite, Used copper head gasket spray 4 layers on intake and crossover ports, ultra blue on
coolant ports and ends of manifold.
NEVER a leak of coolant or oil. over many many times..
problem is sucking air into #5 cylinder port.
Here are photos of area. Next step is to clean up surfaces.
The intake surface on the head probably needs milled. It looks like top isn't sealing as well. I have never had this issue on multiple Olds, stock and Edelbrock intakes. Do you use the 3M abrasive rotary pads to clean the surface? I use the rotary pads and Permatex Aviation sealant, same as Gaskasinch around the intake ports. The 3A are crack prone, poor flowing heads but never heard of this issue.
It looks like you have a even sealing surface. I’m basing this on the even imprint of the turkey tray gasket.
Once everything is clean, lay a straightedge across the head and intake. Make sure those surfaces are flat.
I would use the thick composite gasket. Cut off the intake/coolant part of the old turkey tray, leave it in the lifter valley. That will keep hot oil off the bottom of the manifold. Run a thin bead of silicone around each intake port, on both side of the gasket. Use a thicker bead of silicone on the end rails. Reinstall the manifold, clean and oil the threads of the manifold. Torque the bolts in steps and evenly. Retorque after a couple heat cycles.
I know using silicone around the intake ports isn’t the textbook installation method. But since this is a ongoing problem, and you have no interest in tearing into the engine further, I’d say that is your best option. I can’t imagine the head or manifold being so warped that the composite gasket and sealer can’t seal things up.
Have you tried a thinner intake gasket ?. I had a similar issue with my current 350. The fix is machining the intake or heads etc etc. But the longest a set if gaskets lasted was .030 cometic intake gaskets. They didn't last long because I screwed it up. So if you flip and oblong the bolt holes on the BBO Intake gaskets the ports line up. Obviously bigger but they seal. I didn't do that and had a sliver of sealing surface at the top of the port. Currently have the mr gasket intake gaskets and they are wicking oil. So it's gonna devolp and vaccum leak yet again. But try thinner intake gaskets. It worked for me until the top of the port seal area blew out. Literally had a 16th of sealing material. But they lasted over a year.
I know using silicone around the intake ports isn’t the textbook installation method. .
Been there done that.. SCE 0.062 accuseal, also tried Copper RTV gasoline eventually eat it up.. and leaked...
Fred[/QUOTE]
I figure the thick gasket and sealer is “well, I’m out of ideas” fix. If things don’t work going by the book, make it up as you go along!
And if the thick gasket and sealer doesn’t work, I’m out of suggestions.
And the turkey trays primary purpose IS to keep the hot exhaust crossover from cooling the oil. I forgot all about that. The exhaust crossover is blocked on my car, has been for years.I still use a tray to keep the hot oil off the intake. Classic case of tunnel vision.
Came across this Remflex material, anyone ever try this for an intake manifold?? I see they make a gasket for a Chevy in-line 6 which has intake and exhaust ports.
I use thin cometics to cure problem. Intake was not milled with thicker gaskets it was pulling away from the bottom so to speak. No vacuum leaks but would wick oil with the composite style paper gaskets. The thin cometics acted like a milled surface. That fixed it for me.
Came across this Remflex material, anyone ever try this for an intake manifold?? I see they make a gasket for a Chevy in-line 6 which has intake and exhaust ports.
Called Remflex today. Yes this material can be used for an intake manifold. They did mention that if torqued too much the material might crumble and get sucked into the intake flow.. Remflex recommended 20 lbs torque.. Remflex offered no Ra roughness number for the surface.. Crankcase oil should have no effect.. Gasoline/ethanol no effect. Also read turbo guys use 30psi boost with success.. I measure my intake vacuum at 22 Hg which equates to about 10.8 lbs psi..
Again Remflex makes Chevy inline 6 gasket with both intake and exhaust and reviews are great.
OK took some measurements around manifold.. poked a feeler guage around each intake and water port, between each head and the intake. Most I could not put a feeler guage in at all..
near #5 cylinder about 0.0015"..
Pulled the intake off. Lesson learned: "use a very small amount of clay"
Here is what heads and intake sides look like. Seem like very good match... One thing I read in the previous posted articles is to not have a perfect match as it is better to have a bit more crush at the bottom to seal better against oil weep into the gasket.. Not what I am seeing here.. very flat to flat.
Ok cleaned everything up and ran a big flat file across the intake sides. kind of surprised to see a bit of high and low spots as this intake is one I got the last smog test, it was and originall and I had it milled 0.005".just to clean it up a bit..
Ports 7, 5 and crossover.. different angle view Ports 7, 5 and crossover..
In the Flatness and Surface Finish article posted before. It says intake should have 30-60 Ra surface roughness to better hold the gasket from blowing out. Anyone ever pay attention to this?? I am thinking of sanding down the high spots down with grit 150 sandpaper = 42 Ra stuck to a log flat file
That poor finish on the intake manifold surface could very well be the culprit. Looks like the machinist did not have the individual cutters on his rotary broach set properly or the manifold was not secured adequately to prevent chatter. I recently had to replace the exhaust manifold on one of my vehicles. The original is cast iron and the replacement is tubular with a 1/2" thick flange. It looked great with nice looking welds but I decided to check it with a strait edge prior to mounting and discovered almost .015" warpage on the flange mounting surface, center being low. Not having the time nor wanting to spend the money with a machine shop to correct this, I checked the surface of one of my work benches with a strait edge and found it very strait and sturdy. I next went to my local auto parts store and found some "stick on" self adhesive type body file sheets of various grits, 2 3/4" wide X 16 1/2" long. It took 4 sheets of 32 grit followed by 2 sheets of 80 grit stuck to the top of my work bench to satisfactorily true up the high carbon steel flange. I then followed with a standard 9 X 11 sheet of 100 grit for finishing. Your choice of grit will vary depending on the material of the manifold, iron or aluminum. I tend to be conservative and tried starting first with 80 grit paper but found it was not cutting the steel adequately.
OK Some will probably cringe over this.. SO used 150 grit adhesive back sandpaper 15 1/2" log from Home Depot and put it on a 28" auto body Hoagie type hand sander with all stiffing rods in it.. . to get an Ra of about 42 to clean up some of the wavyness.
Did about 5 strokes each of a 45 Degree cross hatch one way and then the other then about the same 5 strokes back and forth straight with even pressure until it looked like the photos on both sides of the manifold.
That poor finish on the intake manifold surface could very well be the culprit. Looks like the machinist did not have the individual cutters on his rotary broach set properly or the manifold was not secured adequately to prevent chatter. I recently had to replace the exhaust manifold on one of my vehicles. The original is cast iron and the replacement is tubular with a 1/2" thick flange. It looked great with nice looking welds but I decided to check it with a strait edge prior to mounting and discovered almost .015" warpage on the flange mounting surface, center being low. Not having the time nor wanting to spend the money with a machine shop to correct this, I checked the surface of one of my work benches with a strait edge and found it very strait and sturdy. I next went to my local auto parts store and found some "stick on" self adhesive type body file sheets of various grits, 2 3/4" wide X 16 1/2" long. It took 4 sheets of 32 grit followed by 2 sheets of 80 grit stuck to the top of my work bench to satisfactorily true up the high carbon steel flange. I then followed with a standard 9 X 11 sheet of 100 grit for finishing. Your choice of grit will vary depending on the material of the manifold, iron or aluminum. I tend to be conservative and tried starting first with 80 grit paper but found it was not cutting the steel adequately.
One of the carbide inserts may have been sticking out a little in the MILLING CUTTER (not a rotary broach). He appears to have been traversing at fast feed rate, and I see no evidence of chatter.
Originally Posted by FStanley
For the Heads side I just cleaned them up and ran a flat file to check for flatness. Seemed to be pretty good so I left them as is... I think you have the right idea, but I would have used a 1/2" (3/4" would be better) thick piece of glass with the adhesive backed sandpaper. "Plate glass" is surprisingly flat and straight. Have the glass place make sure the edges are smooth so you don't get cut. By using a very thin film of grease, you can lay the plate glass on the surfaces and see were it contacts. A file or body file are for rough work and not certified for flatness.
I would like to see better pics of the head surfaces in the middle. All in all, I think you have the right idea.
........Just my two cents worth.
Passenger Side Driver Side
Last edited by OLDSter Ralph; Nov 8, 2020 at 01:52 PM.
Reason: typo
Looks good. I would not expect to see warpage on the cylinder head. Have you verified it flat with a strait edge and feeler gage? Have you checked everything again since working it? Keep us informed as to the outcome. Nice work Fred.
Looks good. I would not expect to see warpage on the cylinder head. Have you verified it flat with a strait edge and feeler gage? Have you checked everything again since working it? Keep us informed as to the outcome. Nice work Fred.
OK Got some machined steel and did a check of head warpage. I could not find anything significant like really none.. I used the machined steel wrapped with 150 Grit sandpaper and sanded up a bit. I covered the valley tray with cardboard, then used the shop vac, then blew everything out, especially head screw holes,.. , then used the shop vac AGAIN to make sure no grit was left behind, then cleaned off with wypall with acetone, then blew and shop vac'd again.
Got the Remflex material.. not perfectly smooth.. mmm also practiced cutting it.
has plastic screen in the middle to hold it together...
Used a new gasket I had as a template for cutting the Remflex. Used a chrome valve stem sleeve to act as a bolt hole cutter. Used the other side of the wife's plastic cutting board to cut out Remflex.. Took a few wacks to get sleeve to cut through Used Exacto knife to cut out port holes...
Last edited by FStanley; Nov 18, 2020 at 12:22 PM.
I re-read the original post, and something isn't adding up...
You stated the smog test failed because of high NOX. That makes me believe HC and CO are good, since you didn't mention they are too high and outside of state limits.
Subsequently you state that the exhaust crossover in the intake manifold is plugged.
The intake manifold crossover passage is what 'feeds' the EGR valve. If the passage is plugged, the EGR valve has no source of exhaust gas, so even if everything else is correct, and the EGR valve is opening correctly, it will not be doing it's intended purpose.
What is the EGR's intended, and only purpose? To lower NOX!!!
Let's start from the beginning... What are the actual numbers for HC, CO, NoX and CO2?
If what I have summarized above is correct, your emission failure is because of an intentionally plugged exhaust crossover, unintentionally disabling the EGR system, causing the high NOX readings...
If you make gaskets again, cut some tubing (fuel, hydraulic etc.) 6" long, same size as the holes or a little larger. . Sharpen the end with a 60 degree tool inside. Use it like a hole punch and it will cut clean holes. Be sure to poke the "slugs" out after each hole. You could also use it to punch the corners for intake ports to cut them out easier. Get a cheap kitchen cutting board and you're all set.
"Subsequently you state that the exhaust crossover in the intake manifold is plugged."
Where did I say this in my posts?? no it is not plugged..
The readings are in this photo. Problem is that #5 cylinder is leaking, which I think is being caused by the EGR valve heating up the area and the heat cycles cause the seal to break.
NOX is high due to #5 sucking in air and making the mixture lean and high NOX. I've seen this many times before. Same ole problem..
