Skidplate Posted December 5, 2023 Share Posted December 5, 2023 (edited) 37 coupe with original 248 engine. As most of you know, it's been one thing or the other for what seems like forever with this car. Been doing the final tuning for some time now and probably have this (not even 100 hp) stock engine as tuned as its going to get. Now the problem seems to be, an hour or so on the road and I can't keep the engine gasses from running me out. I've added a later version side gas exhaust tube to vent the passenger side of the engine gasses back past the fire wall. That's helped a bit. The driver side crankcase vent is just there toward the back of the engine and there's nowhere to vent that. I can't believe that people stood that much trash floating into the cab for very long. I am open to input. Or should I just don my respirator and (pardon the expression) Suck It Up. Edited December 5, 2023 by Skidplate (see edit history) Link to comment Share on other sites More sharing options...
nat Posted December 5, 2023 Share Posted December 5, 2023 21 minutes ago, Skidplate said: I can't keep the engine gasses from running me out. Other than the crankcase breather, all the fumes should be blown out behind the rear bumper. The addition of a PCV valve might help with excessive crankcase fumes. It seems like there must be an exhaust leak and/or holes in the bodywork. Holes in the trunk can circulate fumes through the cabin. Maybe try some sort of extension on the tailpipe to see if that makes a difference. Link to comment Share on other sites More sharing options...
Skidplate Posted December 5, 2023 Author Share Posted December 5, 2023 A PCV was my thought also but this engine actually has three gas escape routes. The top valve cover at the rear, the passenger side cover that has the down tube and the driver side vented cover that sets below the manifolds and to the rear. I'm not even sure a PCV valve would work in such a well ventilated engine. The exhaust pipes is new from end to end, and one would think I'd hear it if it were leaking. And the gas is more of an Oil gas anyway, but I won't rule anything out. I'm wondering if my rings are just allowing so much past, the exhaust is blowing out through the block. Probably should do a compression check now that I've put a few miles on it. I rebuilt the top end but not the bottom. 1 Link to comment Share on other sites More sharing options...
nat Posted December 5, 2023 Share Posted December 5, 2023 8 hours ago, Skidplate said: the gas is more of an Oil gas Valve cover leaking on the exhaust manifold? Link to comment Share on other sites More sharing options...
EmTee Posted December 5, 2023 Share Posted December 5, 2023 6 minutes ago, nat said: Valve cover leaking on the exhaust manifold? Check the valve cover. I replaced the gasket on mine and it still leaked until I eventually determined that I simply didn't have it tight enough. The three nuts that hold the cover down need to be tighter than you'd think -- but don't over tighten the center bolt, or it will distort (i.e., spread) the cover. I gradually tightened mine by giving the bolts 1/4 ~ 1/2 additional turn when warm until the leak stopped. Link to comment Share on other sites More sharing options...
Wayne R Posted December 5, 2023 Share Posted December 5, 2023 Hello EmTee, talking about valve cover tight , Skidplate i hope you dont mind me coming in on this, but last time i fitted a valve cover on a Buick was about 15 years ago, but when i owned Mercedes ,Alfa Romeo, Porsche and other makes and models ,nearly all recommended when fitting valve gaskets on, that you apply a suitable sealant to the under side of the actual valve cover, but not on the head, ,i would like to know here is this usually the way Buick members fit valve covers there cars today. Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted December 5, 2023 Share Posted December 5, 2023 (edited) Skidplate, two of what you are calling "vents" are in fact the fresh air inlet to the engine. The one on the valve cover is to let fresh air into the top of the engine, the one beneath the manifold at the back channels air into the lower crankcase. The outlet is the one on the passenger side where the road draft tube attaches. ALL MUST BE CLEAN. Ben Edited December 5, 2023 by Ben Bruce aka First Born (see edit history) 3 Link to comment Share on other sites More sharing options...
EmTee Posted December 5, 2023 Share Posted December 5, 2023 It's sounding to me like this engine may have a fair amount of blow-by. Like Ben said, the vents need to be clean - particularly the road draft tube, which generates a vacuum as the car is moving and is particularly susceptible to sludge accumulation from the lifter gallery. The vent in the valve cover relies on pressure generated by air building-up at the firewall to force fresh air into the rocker area. The extension added to the draft tube could interfere with 'draft' generation. 1 Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted December 5, 2023 Share Posted December 5, 2023 Depends, EmTee. Later years, the draft tube, connected the same place, extended back past the engine. Ben Link to comment Share on other sites More sharing options...
Steve_bigD Posted December 5, 2023 Share Posted December 5, 2023 Yes, I agree with EmTee, sounds like high blowby caused by worn piston rings. When I got my 38 Special the fumes would seep into the cab when stopped and if I took the oil filler off with the engine idling it looked like a steam locomotive. When I took the engine apart, my compression rings were virtually dust and the pistons were partially eaten away at the top. The exhaust gas blowby causes high pressure in the crankcase, blowing out oil fumes and exhaust gas. I would recommend that you check your compression to verify bad rings. All of mine were under half of the spec with a couple under 30lbs. Steve D 2 Link to comment Share on other sites More sharing options...
Skidplate Posted December 5, 2023 Author Share Posted December 5, 2023 (edited) I gave it a lot of thought last night and suspect the valve cover is indeed probably more than half the problem. Not discounting the blow by potential but maybe address THAT once I'm ready to rebuild the bottom end. Can we say Kicking and Screaming? Oh, and thanks for the oil filler hack. I've never thought to look at that. I WILL check my compression again though as it's not been done since putting these last 500 tuning miles on it. Anyway, I refrained from doing a good permatex seal on the cover gasket because I wanted to be able to adjust the valves again (or at least, on occasion). But indeed, I have been getting oil around my plugs during the last numerous tuning and plug checking processes. Guess maybe I'll do one final couple hour warm up run and adjust the valves one last time (they've actually held pretty well) then do a good permatex top and bottom. And speaking of that... I finally sprung for a bottle of the original Permatex with the brush on the lid. You know, the old fashion stuff that we all grew up with. And Damn.... that stuff is expensive. I'm inclined to use it just because of what I had to pay for it. Oh, and that was a "well back in MY day...blah blah blah". Sorry, just had to get that out. Cheers Edited December 5, 2023 by Skidplate (see edit history) Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted December 5, 2023 Share Posted December 5, 2023 That "oil around the plugs" thing can PROBABLY be fixed. If you mean, oil accumulates around the plugs while driving. The holes the bolts for the short, low side rocker arm stands use are through holes directly above the plugs. The bolt threads must be treated with sealer to prevent oil wicking down . Ben 2 Link to comment Share on other sites More sharing options...
nat Posted December 5, 2023 Share Posted December 5, 2023 It's been a long time since I've had the valve cover off a straight 8 Buick so I don't remember those specifics but most valve covers are distorted from over tightening. While it's off, check the flange to see if it's flat and parallel to the head surface. 7 hours ago, Skidplate said: original Permatex with the brush on the lid. Aviation cement? A real horror show to remove. RTV sealer is good stuff. Use a light bead and snug the cover. Tighten it the rest of the way after it's cured. Link to comment Share on other sites More sharing options...
neil morse Posted December 6, 2023 Share Posted December 6, 2023 This is what I used. As noted above, just use the glue between the valve cover and the gasket. 1 Link to comment Share on other sites More sharing options...
Grimy Posted December 6, 2023 Share Posted December 6, 2023 @neil morse bought it for the graphic on the can; he didn't care if the stuff works! 🙂 3 Link to comment Share on other sites More sharing options...
Motorpirate Posted December 6, 2023 Share Posted December 6, 2023 Another vote for "Gaskacinch". We use it on the race car, seals like Permatex but on disassembly you can just pull the gasket off. And many times re-use it! Link to comment Share on other sites More sharing options...
EmTee Posted December 6, 2023 Share Posted December 6, 2023 20 hours ago, Skidplate said: Anyway, I refrained from doing a good permatex seal on the cover gasket because I wanted to be able to adjust the valves again (or at least, on occasion). But indeed, I have been getting oil around my plugs during the last numerous tuning and plug checking processes. Guess maybe I'll do one final couple hour warm up run and adjust the valves one last time (they've actually held pretty well) then do a good permatex top and bottom. I used just enough Permatex #2 to hold the gasket to the valve cover during installation. I didn't put any sealer on the side that meets the head, as I also want to remove the cover for maintenance. I have a cork/rubber composition gasket. I have sometimes smeared a thin coating of grease on the gasket surface on a new gasket to help it seat against the cast iron head. I didn't do that on my '38, as the gasket was already on the engine. My experience with the valve cover is it requires regular checks on the bolts as the gasket 'takes a set' until the residual torque stabilizes. If the valve cover is leaking, you should see oil pooling in the depressions on the intake manifold side. If you see oil pooled under a spark plug, it could be coming in through the bolt threads of the rocker shaft support directly above the plug, as @Ben Bruce aka First Born mentioned. The fix for that is to remove the bolt, clean the threads with brake cleaner and apply sealer to the threads before reinstalling the bolt. I used Permatex #2 on mine. 1 Link to comment Share on other sites More sharing options...
Skidplate Posted December 6, 2023 Author Share Posted December 6, 2023 Not sure how I overlooked bolt holes above the plugs but maybe at least that would explain how the valve cover seal looks so clean. I'll look today. Link to comment Share on other sites More sharing options...
neil morse Posted December 6, 2023 Share Posted December 6, 2023 10 hours ago, Grimy said: @neil morse bought it for the graphic on the can; he didn't care if the stuff works! 🙂 Maybe so. But don't forget that you're the one who recommended this stuff to me in the first place! 😆 2 Link to comment Share on other sites More sharing options...
nat Posted December 6, 2023 Share Posted December 6, 2023 That is a great label. Does anyone know what that image and gasket sealer have in common? Link to comment Share on other sites More sharing options...
EmTee Posted December 7, 2023 Share Posted December 7, 2023 9 minutes ago, nat said: Does anyone know what that image and gasket sealer have in common? It must have something to do with the "Belt Dressing" claim... Link to comment Share on other sites More sharing options...
Skidplate Posted December 7, 2023 Author Share Posted December 7, 2023 (edited) Years ago I'll never forget. I was trying to change the spark plugs on my 80 something Trans Am. I was cussing and throwing things because short of pulling the engine, there was absolutely NO WAY I could figure how to get at those plugs. Then the resident Old Guy suggested I pull the front wheels off. Promptly disregarding this advice and after numerous more other attempts trying everything and anything else, I finally (and disgruntly) jacked up the front and removed both front wheels. And what did I see? Low and behold 4 spark plugs on each side just poking out behind where the tires would have been in front of god and everybody. Imagine that. Fast forward to now and I'll be the first to say, of all the kindly and good recommendations... looking under the overhang above the spark plugs for oil leaks was NOT on my list of viable problem spots. Hell, I wasn't even going to mention the oil around the plugs because it just couldn't be anything other than a leaky gasket. But with the help of my trusty phone camera and prior knowledge (I would have NEVER found this) bigger than sh*t there they were. Above every plug was a very sneaky and very leaky bolt hole. Ben you are brilliant and you have my undying respect. Even after having the head off and inspecting it every way but loose, I never noticed the bolt holes just above the plugs. If ever we meet, I'll buy the first (and second) round. So having now sealed all the threads up but not yet putting the cover back on. I'm letting the valve cover gasket dry in place before I put it on tomorrow. I don't know what other mysteries lie ahead before ALL the bugs are out of this engine, but for now, progress has definitely been made. Oh and I got to use some of that wiz bang, expensive as h*ll Permatex. Life is good. Edited December 7, 2023 by Skidplate (see edit history) 3 1 Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted December 7, 2023 Share Posted December 7, 2023 Thanks for the kudos, sir. I reckon brilliant is a little much, but I will take it. That is just one of several things we have learned over the years on these Straight Eights. Ben Link to comment Share on other sites More sharing options...
neil morse Posted December 7, 2023 Share Posted December 7, 2023 38 minutes ago, nat said: Does anyone know what that image and gasket sealer have in common? The answer to your question is that studies have shown that virtually 100% of gasket sealer buyers are men! 😁 1 3 Link to comment Share on other sites More sharing options...
Shootey Posted December 7, 2023 Share Posted December 7, 2023 I’ll offer a totally irrelevant point on straight eight Buick coupes. Skidplate I love the tough look of your car. It reminds me of the 1939 Chevy that Juan Manuel Fangio raced in the Premio Argentino de Carreteras, all cut down and nasty. In the ‘90’s I bought a 1938 Century coupe that was hotrodded as a presumed drag racer. I was a purest and proceeded upon a 10 year body off restoration. It won trophies at Hillsborough, Silverado and Lafayette. That was all fun but a part of me said I should have just left it the way it was. Those Buick coupes as racers were a lot of fun with a lot of character. Link to comment Share on other sites More sharing options...
Skidplate Posted December 7, 2023 Author Share Posted December 7, 2023 Thanks. Glad you like it. As do I Link to comment Share on other sites More sharing options...
Larry Schramm Posted December 7, 2023 Share Posted December 7, 2023 I might have missed it, but are all of the body seams sealed tight in the trunk? Link to comment Share on other sites More sharing options...
Skidplate Posted December 7, 2023 Author Share Posted December 7, 2023 Everything is factory sheet metal with no rust, so I would say yes; all is sealed. I did the "gasses test" (recommended by BigD) at the filler lid and smoke definitely came out but it didn't blow out. It just kinda rolled. I just don't remember there being that much of an issue even with worn out engines to let those gasses in the cab. I also ran the engine gas exhaust back behind the firewall via a later model tub assembly. So now it at least clears the firewall. During the paint and body phase I sealed all around the doors except for along the bottom. And that was just because I could never get the trim to stick. I wonder if the gasses are being pulled up from under the doors. Just thought of that. Link to comment Share on other sites More sharing options...
nat Posted December 8, 2023 Share Posted December 8, 2023 (edited) 1 hour ago, Skidplate said: I wonder if the gasses are being pulled up from under the doors. Just thought of that. The trunk lid is more likely. Add a temporary snorkel to the tail pipe to rule that in or out? Edited December 8, 2023 by nat . (see edit history) Link to comment Share on other sites More sharing options...
Skidplate Posted December 8, 2023 Author Share Posted December 8, 2023 The trunk has new rubber all around. Not likely there. Link to comment Share on other sites More sharing options...
Skidplate Posted December 9, 2023 Author Share Posted December 9, 2023 Went back and double-checked the trunk. Really good seal all the way around. Also checked my compression. From everything I can tell, this engine had never been apart until I pulled the head, replaced all the springs and valves, shaved the head just a touch and replaced the gasket and reinstalled. Admittedly I wasn't sure if everything down below was still good but every indication gave me a strong 60/40 chance of a good bottom end. I also plasti-gauged the main bearings and tightened up the clearance a bit. Doing the compression check, it might not be great but they were all spot on 70psi. So with that, and I really really don't want to pull the engine and rebuild it... I'm going to say my compression is OK. Oh, and I installed the seal at the bottom of the doors. All the others went on fine but for some reason, those bottom seals were an absolute bear. So I kinda gave up on it... until now. I really doubt it'll have any impact on the gaseous issue but it seems everything I've avoided earlier in the restoration and then fixed later because of something else has basically paid off in some other unforeseen way. So the door seals are drying over night and maybe I'll take it out tomorrow for test drive number who-knows-what and all will be great. It's funny how the final sorting out almost seems to be the most difficult. Oh, and the bolt holes above the spark plugs are still leaking. Obviously I didn't do it properly. This may be something else I readdress later/again the next time I pull the valve cover. Really hoping the doors solve the problem. Link to comment Share on other sites More sharing options...
nat Posted December 9, 2023 Share Posted December 9, 2023 16 minutes ago, Skidplate said: the bolt holes above the spark plugs are still leaking. Aviation cement would be fine for sealing those. Link to comment Share on other sites More sharing options...
XLNDRVR Posted December 9, 2023 Share Posted December 9, 2023 On 12/6/2023 at 7:29 AM, EmTee said: I have a cork/rubber composition gasket. Not meaning to hijack the thread. Any recommendation for brand and where to purchase? Looking to replace my failing cork gasket with something proven to be more robust. Also, I too have benefited from the experience of others here when it comes to resolving the oil around the spark plug issue. Love it when gems of info like that are shared. Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted December 9, 2023 Share Posted December 9, 2023 3 hours ago, XLNDRVR said: Not meaning to hijack the thread. Any recommendation for brand and where to purchase? Looking to replace my failing cork gasket with something proven to be more robust. Also, I too have benefited from the experience of others here when it comes to resolving the oil around the spark plug issue. Love it when gems of info like that are shared. Best Gaskets. Olsen Gaskets in Port Orchard , WA. Probably can order from your local auto parts store as well. Ben 1 Link to comment Share on other sites More sharing options...
EmTee Posted December 9, 2023 Share Posted December 9, 2023 I personally avoid the non-cork, black 'fiber' type of cover gasket. The one on the pushrod cover of my '38 Buick was old and completely saturated with oil. The cork/composition ones seem to hold up better for me. I replaced the pushrod cover with one of those from Olson's (which I recall may have actually been a 'Best' gasket) and used a thin coat of Permatex gasket maker to first adhere it to the cover before installation. No leaks! 1 Link to comment Share on other sites More sharing options...
Brian_Heil Posted December 9, 2023 Share Posted December 9, 2023 (edited) Valve cover? What’s a valve cover? 😀😀😀 Edited December 9, 2023 by Brian_Heil (see edit history) 2 2 Link to comment Share on other sites More sharing options...
DonMicheletti Posted December 9, 2023 Share Posted December 9, 2023 Key to the rocker stanchion bolts not leaking is thorough cleaning of the bolt holes. I use a round wire brush, solvent and a an electric drill to clesn them before installing the bolt with a sealant 1 Link to comment Share on other sites More sharing options...
XLNDRVR Posted December 9, 2023 Share Posted December 9, 2023 13 hours ago, Ben Bruce aka First Born said: Best Gaskets. Olsen Gaskets in Port Orchard , WA. Probably can order from your local auto parts store as well. Ben Thank you, sir! Looks like Best gaskets can be found multiple places. 30005E for me. Link to comment Share on other sites More sharing options...
Skidplate Posted December 9, 2023 Author Share Posted December 9, 2023 Brian, now you're just showing off. Sweet. Link to comment Share on other sites More sharing options...
Brian_Heil Posted December 9, 2023 Share Posted December 9, 2023 When I can’t smell lube burning off on the exhaust manifold I must have an issue. 1 1 Link to comment Share on other sites More sharing options...
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