STEVE POLLARD Posted September 7, 2023 Share Posted September 7, 2023 My truck engine is a 396 BB, it has about 88,000 miles on it. I have noticed on start up, it smokes a little until it warms up. Well the other morning, I decided to drive the truck to work - no issues. On the drive home, while at a red light, the driver next to me yelled and said that "a burning odor is coming from your truck". I can do basic maintenance on my vehicles, but if it came to an engine rebuild, I'm out of my league. So for the experts here, does this sound like a possible rebuild ? Just as a note, the truck's performance is great, so I was a little surprise the hear about the odor. Link to comment Share on other sites More sharing options...
95Cardinal Posted September 8, 2023 Share Posted September 8, 2023 Smoke at startup without any other negative symptoms usually means that your engine needs new valve stem seals. The parts are cheap (typically under $25 for an engine set). Installation requires removal of the rocker arm covers, holding the valve (usually with compressed air or cord) in the fully closed position while loosening the rocker arms , removing the valve spring retainers, valve springs and any remnants of the old seals. Then, you'll need to install the new seals (be sure to use the sleeve to protect the new seals from being cut or nicked during installation), then reinstalling the springs, retainers and rocker arms. Finally, set the valve lash and reinstall the rocker covers. 2 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 8, 2023 Author Share Posted September 8, 2023 Thanks Joe ! Link to comment Share on other sites More sharing options...
rocketraider Posted September 8, 2023 Share Posted September 8, 2023 Is the engine using any appreciable amount of oil? Odor: I've noticed some modern gasoline blends have a burnt smell at the tailpipe, like grease or oil. Yet the tailpipe is dry and not sooty like burning oil or running rich would indicate. Is the engine leaking any oil onto exhaust system? That could also be the smell. 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 8, 2023 Author Share Posted September 8, 2023 31 minutes ago, rocketraider said: Is the engine using any appreciable amount of oil? Odor: I've noticed some modern gasoline blends have a burnt smell at the tailpipe, like grease or oil. Yet the tailpipe is dry and not sooty like burning oil or running rich would indicate. Is the engine leaking any oil onto exhaust system? That could also be the smell. Glenn - I just checked the log book, oil change / full tune up was done in the Fall of 2021, it's been driven 100 miles since. I'm down a quart - maybe a quart 1/2.... I don't see anything on the exhaust ( new exhaust was installed in Fall of 2021 as well) . Driving along, you don't smell anything in the cab, that's why I was surprise to hear about the motorist that pulled up next to me.... now that I think of it, on the drive home, normally people are riding my tail, but they were at least 10 car lengths behind me.... Link to comment Share on other sites More sharing options...
rocketraider Posted September 8, 2023 Share Posted September 8, 2023 Ai... That's a lot in 100 miles. That's a lot in 1000 miles even for a big-block. Read the plugs to see if any are oil fouled. Past that sounds like time for a compression check and valve stem seals. Possibly worn valve guides. A leakdown test would show if there were ring problems but not everyone has a leakdown tester. Try this. On off chance some rings may be sticking from lack of use, change oil and substitute a quart of blue Rislone, Marvel Mystery Oil or even Dexron ATF for a quart of oil. Then drive it. Might free up rings where they can move in their lands as designed. Decades ago if the local Chevy dealer got a car in with complaint of high oil consumption, they'd change oil with Sinclair 20 weight and instruct the owner to drive it 500 miles, then repeat the process. If oil consumption was still unacceptable after 1000 miles then they'd tear down the engine. I'm told Sinclair was Chevrolet's "factory fill" oil specification, and Cadillac and Oldsmobile used Kendall. 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 8, 2023 Author Share Posted September 8, 2023 2 minutes ago, rocketraider said: Read the plugs to see if any are oil fouled Ok.... I'm off for the next few days, so I should get to it.... Thanks ! Link to comment Share on other sites More sharing options...
JACK M Posted September 8, 2023 Share Posted September 8, 2023 I had a 454 in a work truck years ago. There were no exhaust manifold gaskets from the factory. I fixed that, there were some heat shields under the manifold bolts that are easier to toss than replace. It needed better valve cover gaskets too. Probably not your issue, I'm just recollecting. 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 8, 2023 Author Share Posted September 8, 2023 (edited) 2 hours ago, rocketraider said: Read the plugs to see if any are oil fouled Storm coming thru the area at this time, so I'm back in the garage.....I only pulled three... they only have 100 miles on them..... Edited September 8, 2023 by STEVE POLLARD (see edit history) Link to comment Share on other sites More sharing options...
GARY F Posted September 8, 2023 Share Posted September 8, 2023 If the gas has been in there since 2021 it could be rotten gas. I had that crap in my 63 GP for a year and started it up and it ran lousy and smoked and smelled. I siphoned all the gas I could and put in new gas. No problem after that. 1 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 8, 2023 Author Share Posted September 8, 2023 4 minutes ago, GARY F said: If the gas has been in there since 2021 it could be rotten gas Good point Gary.... I had 1/4 tank and I just filled it with Sunoco 93 high octane last week....that's one thing with this big block compared to my old truck that had the 350 in it, it goes thru the gas Link to comment Share on other sites More sharing options...
95Cardinal Posted September 8, 2023 Share Posted September 8, 2023 6 hours ago, STEVE POLLARD said: Glenn - I just checked the log book, oil change / full tune up was done in the Fall of 2021, it's been driven 100 miles since. I'm down a quart - maybe a quart 1/2.... I don't see anything on the exhaust ( new exhaust was installed in Fall of 2021 as well) . Driving along, you don't smell anything in the cab, that's why I was surprise to hear about the motorist that pulled up next to me.... now that I think of it, on the drive home, normally people are riding my tail, but they were at least 10 car lengths behind me.... @STEVE POLLARDThat's a LOT of oil consumption, more than can be expected due to some smoking at start-up. Glenn (@rocketraider) is correct; follow his advice: "That's a lot in 100 miles. That's a lot in 1000 miles even for a big-block. Read the plugs to see if any are oil fouled. Past that sounds like time for a compression check and valve stem seals. Possibly worn valve guides. A leakdown test would show if there were ring problems but not everyone has a leakdown tester. Try this. On off chance some rings may be sticking from lack of use, change oil and substitute a quart of blue Rislone, Marvel Mystery Oil or even Dexron ATF for a quart of oil. Then drive it. Might free up rings where they can move in their lands as designed." Those plugs (especially 1 & 3) look like they're seeing a lot of oil... 1 Link to comment Share on other sites More sharing options...
Oldtech Posted September 9, 2023 Share Posted September 9, 2023 I was thinking the plugs looked more like carb is running rich. Do you know it was full 100 miles ago? 2 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 9, 2023 Author Share Posted September 9, 2023 21 minutes ago, Oldtech said: Do you know it was full 100 miles ago Yes, I've only been driving it on short runs... to the local Home Depot when I needed to pick up something or down to the local coffee shop....all of which are a few miles from my home.... the drive into work the other day was the longest that I have driven the truck, about 22 miles round trip. Steve Link to comment Share on other sites More sharing options...
rocketraider Posted September 9, 2023 Share Posted September 9, 2023 Before taking the valve train apart, straighten out a coat hanger and rod out the cylinder head oil return holes. If they're plugged or restricted oil can puddle in the head and get sucked in past valve seals and guides. A set of rocker cover gaskets is cheaper and simpler than all that work with valves. Though you may find busted-up valve seals plugging the oil return holes...😉 4 1 Link to comment Share on other sites More sharing options...
EmTee Posted September 10, 2023 Share Posted September 10, 2023 If the truck has only been driven ~100 miles since being idle for years I wouldn't panic (yet). Get some more miles on it; preferably longer trips (20 ~ 30 miles minimum). A long highway jaunt would help, particularly after adding the Rislone. Make sure that the dipstick is correct for the engine and especially the dipstick tube. I seem to recall several different dipstick configurations were used on the BB engines over the years. Overfilling the crankcase can cause excessive oil consumption. If it was over full, did the old oil smell like gasoline? A faulty fuel pump can leak gas into the crankcase and adulterated oil will easily pass by the rings and valve guides. If unsure, drain and refill with the specified quantity, then check the level on the stick. A PCV problem is another possibility. Check that the plumbing is correct and the correct PCV valve is installed. I wouldn't even think of rebuild, valve job or even valve seals until I had accumulated about 1,000 miles of observation. Is there any evidence of oil leakage? It doesn't take much oil to tinge the exhaust, but a leaky rear main seal can lose a lot of oil pretty quickly. 4 1 Link to comment Share on other sites More sharing options...
61polara Posted September 10, 2023 Share Posted September 10, 2023 The burning odor could be nothing more than valve cover gaskets leaking oil while sitting and building up on the exhaust manifolds. This will start smoking and creates a burning smell. Check the simple things first. 3 Link to comment Share on other sites More sharing options...
Frank DuVal Posted September 11, 2023 Share Posted September 11, 2023 Also if I only put 100 miles on a vehicle in two+ years, I would just add oil if it became an oil burner. It would take 100 years to pay for the overhaul if not longer! Just tell onlookers you are fogging for mosquitos! 🤣 1 Link to comment Share on other sites More sharing options...
STEVE POLLARD Posted September 11, 2023 Author Share Posted September 11, 2023 3 hours ago, Frank DuVal said: Just tell onlookers you are fogging for mosquitos! Well it's one way to eliminate tailgaters ! 1 1 Link to comment Share on other sites More sharing options...
EmTee Posted September 11, 2023 Share Posted September 11, 2023 7 hours ago, Frank DuVal said: Just tell onlookers you are fogging for mosquitos! 🤣 That was the original 265 in my '56 Bel Air. Finally cleared the air with a 283/aluminum Powerglide transplant. Link to comment Share on other sites More sharing options...
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