* Low Transmission Fluid: This is the first and easiest thing to check. Low fluid level can cause all sorts of shifting problems, including sticking in first gear. Check the fluid level with the engine running and warmed up, using the dipstick. Make sure the fluid is also the correct type and condition (not burnt or contaminated).
* Problems with the Linkage: The linkage connecting the shifter to the transmission could be bent, broken, or improperly adjusted. This prevents the transmission from receiving the correct signal to shift. Inspect the linkage for any damage or binding.
* Internal Transmission Problems: This is the most serious and expensive possibility. Internal problems could include:
* Worn or damaged clutch packs: These allow the gears to engage and disengage. Wear can prevent proper shifting.
* Broken or worn shift forks: These components physically move the gears into place. Damage prevents the gears from moving.
* Low internal hydraulic pressure: The transmission relies on hydraulic pressure to shift gears. A leak or pump failure could cause this.
* Damaged or worn synchronizers: Synchronizers match the speed of the gears before they engage, allowing for smooth shifting. Damage can cause grinding and difficulty shifting.
* Governor Problems: The governor controls the shift points in some transmissions. A malfunctioning governor could prevent upshifts.
* Electrical Issues (if applicable): Some transmissions, especially those with electronic controls, might have electrical problems affecting the shifting mechanism. This is less likely in an '83 V150, but still possible.
What to do:
1. Check the transmission fluid level and condition first. This is the easiest and cheapest thing to check, and it could solve the problem.
2. Inspect the linkage: Look for any damage or binding.
3. If fluid is fine and linkage is intact, you'll likely need a professional mechanic. Diagnosing and repairing internal transmission problems requires specialized tools and knowledge. A mechanic can perform a proper diagnosis and determine the best course of action, which may include a rebuild or replacement.
Don't attempt to drive the vehicle extensively while it's stuck in first gear, as this could cause further damage.
