LUVTruck.com

Hey Guys,

I went to have the LUV emission tested the other day and it failed, by a long shot. I never noticed it before, but apparently when Its revved up into the 5-6 range it blows a bit of smoke. I took it to a close mechanic and he said its probably the valve seals. Its a 1978 (g200 i think, not sure, could be g180) with about 172,000 miles on it and I don't think its ever been rebuilt or anything; if it has been, it was a long time ago (pre-1993). I changed the plugs, replaced the air filter, and put a little additive in it, but there hasn't been any improvement.

Im gonna try to register it in Larimer or Weld county where they don't test for emissions, however if I can't, what can I do to make it pass? I'm rather mechanically inclined--I've rebuilt a couple dirt bikes and a quad--however I've never attempted to do much automotive work. I don't have a crane to pull the engine and I'm kinda on a tight budget, so that could cause problems......dad said to sell it, pshh!

Any suggestions?

,Brian

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My Rides:

2002 Mazda B4000 4x4
1978 Chevy LUV - Sold
1990 Kawasaki EX500
2008 Yamaha TTR230

do a compression test and see where the problem is.

i will assume you know how to do that, but if not this is the basic method


pull the spark plug and pull the wire out of the coil so it doesnt start on you.
thread in the tester either with an adapter tube, or just use the hose. (depends on the kit you have)
crank the engine and let it turn about 4 to 5 times and write down the compression figure. do this 3 or 4 times and average out the results
(add them all together and then divide by the number of times you did the test. IE: 110+ 112+ 110+ 108 = 110 Average)
do this for each individual cylinder. this will tell you if your rings are worn beyond spec and if you need to rebuild the engine. (pretty simple in relation to other engines i've done)

if it is indeed the valve stem seals (which is a viable problem) then i would RECOMMEND you rebuild the cylinder head and just get it nice and tuned.
if that's the case, there is a thread on here that you can search for where you can see what i did and how to do it.

hope this helps!

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To the Oquirr hills for awesome thrills! Go-go 4wd, Activate!

What were the failure numbers? Nx0, C02, Hc, etc? If I know them may be able to help with an adjustment.

Adding to Figuarus's good advice. Pulling the head to have it rebuild is a lot of work, but requires little beyond an ordinary set of wrenches. The head bolts take a 10 mm Allen head socket and you need a torque wrench. A manual will be a big help. I got a factory shop manual at www.factorymanuals.com for less than the parts stores want for the second rate Chilton or Hynes.

Once you have the head off, take it to an automotive machine shop. Many of the professionally oriented parts stores have them. Rebuilding a head does call for a bunch of specialized tools.

For occasional DIY use, I suggest a beam type torque wrench.

You can buy a decent torque wrench at Sears that is not a beam torque wrench and is a lot more accurate.

For occasional DIY use, clickers are a PITA. They are more accurate as long as the calibration has been checked and adjusted recently. I have no idea how many head gasket jobs I have done since I bought my beam wrench in 1966, and never a problem. I can't remember when I had to do the one on my truck, but it must be at least 10 years and still going strong.

Brian if you could post the numbers that are too high, that would help diagnose. Leaky valve seals and rings should have no effect on the smog test, at least they have no effect here in CA. We need to assume so much it's hard to say, im assuming the timing is correct, and it did not fail the visual part. I have done so many smog's here I can pretty much use my nose to tell if it will pass. LUV's usualy pass with very little effort, blowby, leaky seals and all.

As for tricks to lower the emissions you can add methenol to the gas, but it helps to know what is wrong before using any "tricks" as it can add to the problem depending on what is causing it to fail. You may just have a clogged up cat from oil residue if it is bad enough.

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LUV Truck Desserter!
76 Daily driver (SOLD)
73 LUV (rusting away at the moment)
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63 Nova
74 Camaro

I might be having the same problems. I had a ? for djewett. I live in Oroville and it sounds like you have a lot of experience with the Cal. emmissions. I've had my luv for about a week and I'm having trouble finding out where all the vacume lines and smog pump hoses go to. THe wiring diagram on the hood leaves out a thing that is located behind the smog pump and has about 4 vacume lines and 3 hoses coming off of it. Do you know what that is and where they all go? ANY help at all would be greatly appreciated. Thanks! Bshelly234, good luck

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1974 Mikado 4x4 50,000 orig. miles

Assuming the smoke it bluish, try using synthetic motor oil. It doesn't smoke nearly as bad, or at all, depending how bad the problem is.

Well i dont want to hijack brians thread, but that is the diverter on the back of the air pump, i have some photos if you pm me your email address that should show what goes where, there is a short curved hose, and some that go to the air cleaner, and ten more i think lol

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LUV Truck Desserter!
76 Daily driver (SOLD)
73 LUV (rusting away at the moment)
---------------------------------------------
63 Nova
74 Camaro

Well Brian, if your truck has a cat. conv. you can guy that stuff that makes the converter real hot. Take it down the highway and get it real hot. That might help. I wish you the best of luck. I'm about to go through the same thing. Sometimes smog can be a real pain!

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1974 Mikado 4x4 50,000 orig. miles

Haha, jk. Its cool.


Thanks for all the help guys, I wish I could give you some numbers from the test, but they never actually tested it. I brought it in (not smoking) and they inspected it and everything, but when they started it up and pulled it forward it blew smoke and they said forget it. Luckily they didn't charge me, but still... I don't have a compression tester, so I'll go buy one and check it.

The thing that I can't figure out though is that it only smokes occasionally. It's really odd, like when the engine is cool-ish, it will smoke real bad, especially when starting from a stop (I completely smoked out my neighbor, hehe) but once its hot, it doesn't smoke at all hardly. On cold days like yesterday it smoked pretty much all day (not quite THAT bad tho), but today, it didn't smoke much at all. Its really odd that it will smoke SO much when cold, I literally couldn't see my neighbor yesterday. I've never seen it that bad before and I think its gotten worse.

The smoke is almost always blueish, kind of like two-stroke smoke, but it doesn't really smell bad unless u get ur nose right up into the pipe at idle. When I had my mechanic look at it, it was warm, so thats why it only was smoking a bit at high rpm.

I was thinking that maybe its the cat thats stopping the smoke when its hot and that its actually smoking all the time, but idk if I even have a Cat, I'll check. What do u guys think? Would valve seals create that much smoke? I started noticing the smoke only a couple weeks ago, so could it be that the rings went bad?

Also, about a month ago my radiator clogged and I over-heated it real bad trying to get home (it was spewing steam and coolant all over the engine by the time I stopped). I know thats REALLY bad, but I was kinda desperate. I ended up leaving it on the side of the road and calling a friend. But could that have contributed to the smoking? I first noticed the smoke a couple weeks after that (I've gotten I new radiator since then).

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My Rides:

2002 Mazda B4000 4x4
1978 Chevy LUV - Sold
1990 Kawasaki EX500
2008 Yamaha TTR230

It is possible you damaged the head gasket when it overheated. Oil could be seeping into the combustion chambers and burning off with blue smoke when you start up. You can pick up a compression gauge pretty cheap. I would suggest doing so and checking the compression. Low on 2 adjacent cylinders is a tip off to a bad head gasket.

As Labman says, check the compression. This can show how much the rings have worn and replace/rebuild may be necessary. Normally smoke on start up means oil running down the valve stems (worn valve stem seals) and into the cylinder causing smoke when you start it back up. So-- valve stem seals may be a good place to start.
And yes smoke may be erratic from bad valve seals.