'79 Blazer Transmission problem

Saxomophone · October 10, 2001

In februari i started to restore my '79 Blazer with 250 6cyl and 350 tranny

it never leaked but after standing still for about 2 months it started to leak transmission fluid.Not enough to worry me but still...

About a month ago i went to work on it and noticed an oil spot as big as the truck itself.Someone told me that it was normal that after a while of standing still the oil starts to work its way down and get's out thru the overflow or whatever but it seems to be a whole lot of oil.

Funny enough the dipstick shows a nice full gearbox

Anyone whpo knows where i should look, it'll be ready in a month or two an i don't want to wreck it.

tia

sax

Torque Junkie · October 10, 2001

That sounds like ALOT of fluid for a little standing seepage, and I've personally never heard of a tranny leaking after sitting for a while....

Did you check the tranny fluid while the engine was at operating temp and idling on level ground after slowly (2 seconds between each shift) cycling from P to R to N to D to 2 and to 1 and slowly back to P?

Whatever is causing that, it doesn't sound good. You have any suspect locations as to where the leak is originating?

-Mike

bobs409 · October 11, 2001

Some do leak after sitting. I had my 69 Chevelle stored in a garage for a few months and when I went to get it out, it had a big puddle of trans fluid under it. Once you start driving it again, it will probably be ok. Mine was.

I heard it was just the old seals doing this. The heat from driving it again expands them. My car hasn't used any fluid since that time.

76BBSub · October 11, 2001

I agree with Bob, this is pretty common on GM auto trannys that sit for awhile. If you go to some of the classic car lots you will frequently notice a puddle under some of the automatic-equipped cars from sitting for so long. As Bob said, it usually goes away with some driving, just make sure to get it nice and warmed up and check the level.

As for the amount leaking, what looks like a quart or two on the floor is usually less than a pint or so, it just looks like a terrible lot when spread out on the floor under your truck. Warm it up, check the level, and you'll be OK.

Jeff

Saxomophone · October 12, 2001

Thank you all for the tips, i feel somewhat better now

One more thing, i've decided to replace the 250 with a 350 v8 out of another blazer.

As i understand correctly there should be no problem fitting it to the TH350 tranny.Has anybody got some experience with this?

And how fast do your rides go? I can't get the 250 above 85mph, besides the v8 sound the main reason for the swap

btw its a 2x4

sax

Torque Junkie · October 12, 2001

The fastest I've ever had my truck ('79 chevy with a 350, Edelbrock Performer Intake/Cam/600CFM Carb, Headers and duals w/ Flowmasters) is 75 on the speedo, which is probably around 80-85. and it had Plenty of breath left under the hood, just not much gear (4.56 + TH350 = very high revs - even with 33" tires)

-Mike

76BBSub · October 15, 2001

I've had my '76 Suburban over 100 mph a couple times, I think she'll do about 115-120 before running out of RPMs. This is a 454 with headers and intake, but otherwise stock (for now) with 100K miles.

Jeff

Saxomophone · October 15, 2001

mmm, the 85mph Torque Junkie talks about isn't actually more than the 250 l6 does now

the 454 from 76BBsub with 115-120 is another story, but that's a whole different engine than the stock 350 now isn't it

strange though, my '68 dodge charger with 383ci 4bbl and 3spd auto did an easy 120-125

but let's stick to chevy here

can ayone tell me what a new stock 350 and 454 cost in the states?

just for comparison here in europe

grtz

sax

76BBSub · October 15, 2001

Really depends on the supplier and the amount of power. I think you can get a pretty decent crate engine for about $2000, but it's probably less than 300 HP. More of something for a work truck, not a gearhead's toy.

The 454s are quite a bit more. I am thinking the cheapest Chevy crate engines are at least $3K. Haven't looked lately, though. I can tell you that when you start adding in fuel injection equipment, aluminum intakes or heads, and other performance goodies that the price starts going up exponentially.

Jeff

Torque Junkie · October 15, 2001

I have no doubt I could get my truck to cruise at 100 with the current gearing (4.56 & 3 spd auto), but it'd be screaming at 4500 rpms :0 :0 :0

With an 0.70:1 O/D and 36 tires with the 4.56's, however, at 100 it'd be a meager 3000 rpms I think it could pull 110-120 with that setup, assuming my engine has the torque to move it thru that much air, which I'd immagine it would.

Not that I'd want to finance the fuel it'd inhale while doing that I'm having trouble pulling 10 mpg as it is.

-Mike

Saxomophone · October 15, 2001

10 mpg?

wow that's even worse than the charger

the curent 250 does about 15mpg and it runs real smooth on lpg fuel

but the sound man ... you know what i mean

btw, for all you who saw "bullitt" who knows this:

what setup did mcqueen's mustang have, it sounds murderous

or how can i mimmick the sound and please don't tell me to lose the muffler, my neighbours would have me for breakfast

btw Torque Junkie, i'm thinking of lowering the truck about 5" and slap on some nice 15" rims with 275x10x15 yokohama's

so i'm afraid the mpg's will take a turn for the worse

while typing this i'm realizing it's doing overtime season again

greetz

sax

Torque Junkie · October 15, 2001

sax -

Here is a list of at least some of the cause for my low gas mileage:

Edelbrock Performer Intake, Cam & 600 cfm carb

4.56 rear-end gears

Th350 Tranny (no O/D)

so at 65 mph I'm running at 3000 rpms.

There's probably a couple other things I could do to improve the mileage some, but I'm not sure what yet.... I do plan on swapping the tranny with a 700R4 4 spd Overdrive in the next few months, but other than that I should be able to squeeze a few more mpg out of what I have.

Yes, smaller tires cause the engine to spin faster at the same speed, so your mileage might suffer a bit. I personally dont' care for lowered trucks, so I won't comment on that

-Mike

76BBSub · October 16, 2001

Haven't seen Bullitt in a couple years, and then it was only a clip from the last chase scene. But if memory serves...you need to start with headers, and large exhaust pipes. Stock manifolds and small pipes restrict the exhaust and the noise. My experience is that Flowmaster 2-chamber mufflers have the most "racy" sound of all the street mufflers, especially with headers and big pipes. BUT, the biggest thing required to really make that sound is a high performance engine. Stick all that on a 2-barrel 305 Chevy or 318 Dodge and it won't sound the same. Add a 4-barrel, some compression, an aggressive cam, and the exhaust I mentioned and you'll sound like a race car.

Torque Junkie, when we get your timing sorted out it should help your mileage....don't feel bad, I get 10 mpg with my 454 Sub and 3.73 gears....

Jeff

Torque Junkie · October 16, 2001

Jeff - I know... but it's still depressing every time I go to the pump, and I knew it was going to be like this when I bought an old, slightly modified truck.

I'd be more than happy with 14 mpg. I would hope, with best case scenario (after the 700R4 swap) and me keeping my heavy foot out of those secondaries to pull 16, but that's only aiming very high

Oh, I forgot to mention, last fillup (Sunday) I got 9.3 avg. mpg (24 gallons for 223 miles). Thats an instant ~10% increase with the new carb (I got 8.5 with the old carb, while goin easy on the throttle, i might add), and that's also with me enjoying my 2 new-found barrels. I don't doubt that 10-11 is possible on this next tank if I keep the secondaries closed.

-Mike