89 4.9L Questions

[Acidbath]

I never got a manual with this truck when i bought it, and was wondering what I can do about towing. I'm going to go out and buy a Class V hitch soon, and was wondering if anyone could tell me anything about this motor. How much can i tow, stuff like that.. and if i do a lot of highway driving pulling a load why can't i use the overdrive? 70 MPH in 4th gear dosent seem to make much sence. Thanks

[ModMech]

The 4.9L IS the venerable "300-6", and it's about the toughest engine ever put into a truck. You can pull anything you can stop.

You should have the "HD" 5 speed OD manual trans, and 4th gear is "direct", so depending on the gearing of the axle, 4th is THE gear to tow in if the load (trailer plus what's in the bed) is much over 2,000#. For lighter loads, yes you can use 5th.

Why 4th? Simple, mechanical advantage and engine RPM. It's easier for the engine to move the load in a lower gear, so it heats up less. Direct (4th) is the MOST mechanically efficient gear, so you lose less power in the trans. Finally, with the engine spinning faster, it cools better because the waterpump's flow is based on RPM.

OD is only 0.77 - 0.80 anyway, so it's not a huge change.

[Acidbath]

Well I'll be pulling a trencher / trailer, possibly a bobcat.. anyway, i was just wondering as far as driving on the interstate's and what not. I have heard they use these engines in school busses. So I'm not too worried about what it will pull. Just curious to get the specs on exactally how much i could pull tho. Can I pull my car? Stuff like that.. lol thanks this truck has 197k miles on her, and i'm just now starting to use it like a truck.

[kharrell]

The main limit you should be considering when towing is the weight rating of you pickups brakes and suspension system, the motor is secondairy. With that said several years ago I pulled a 10,000 lb trailer down the interstate with an 87 f-150 with the 300 six, the motor did fine but I was way overloaded and would not do it again with a 1/2 ton pickup. The data plate on your pickups driver side door jam should give you your vehicles:

GVW (Gross Vehicle Weight) This is the max rated weight of the pickup with it fully loaded

GCVW (Gross Comination Vehicle Weight) This is the max rated weight of both pickup and trailer.

your pickups data plate may not display the GCVW. I'm pretty sure a bobcat weigh's at least 5000 lbs, combined with the weight of the trailer that may be too much for a 1/2 ton pickup to safely handle, does your trailer have brakes?

[97chevyman]

if it is a 150 he has the POS M5OD, if you aer towing a lot, might want to swap in a ZF tranny.