I obtained a used radiator to keep as a backup.
I tried testing it, off vehicle, with one of those air pump radiator test kits from auto store.
I sprayed it all over with soapy water and the only place that leaked was at the drain plug, at the sealing surface.
I tightened it as much as I could by hand. I didn't want to break the plastic.
Is there some trick to tightening these up so they are air tight, like a sealant material or something?
Radiator Drain Plug Leakage
Radiator Drain Plug Leakage
'86 Isuzu P'Up Turbo Diesel SpaceCab, 5-spd, 2wd
'86 Isuzu P'up Turbo Diesel 5-spd Longbed, 2d
'86 Isuzu P'up Turbo Diesel 5-spd Longbed, 2d
Re: Radiator Drain Plug Leakage
If I remember right, that drain plug uses either a rubber washer or an o-ring, which might be absent. Have to look at a picture of a new one. /R
'87 Isuzu p'up 4ZD1/2.3 gas, carb'd, 5spd, 4WD, base model, Fed spec
Re: Radiator Drain Plug Leakage
I think the rubber washer was present but it might hav cracked, I’ll have to it check again.
What is the right way to remove the drain plug (so I can reuse it) if I have to replace that rubber washer?
What is the right way to remove the drain plug (so I can reuse it) if I have to replace that rubber washer?
'86 Isuzu P'Up Turbo Diesel SpaceCab, 5-spd, 2wd
'86 Isuzu P'up Turbo Diesel 5-spd Longbed, 2d
'86 Isuzu P'up Turbo Diesel 5-spd Longbed, 2d
-
isuzu Specialities
- Regular Member
- Posts: 286
- Joined: Sun Feb 04, 2024 2:20 am
- Location: West Coast
- Isuzu vehicle(s): Pup Trooper Rodeo
Re: Radiator Drain Plug Leakage
When the valve is closed the cock forces a seal up against a seat located inside the valve body.
This type of valves leak because the seal has shrunk over time and no longer presses tightly into the seat, the seat itself is damaged or both.
First step is to clean the seat inside the valve body and inspect it. The seat shouldn't have any cracks and be uniform in shape & have no high or low spots.
If the seat is undamaged replace the cock seal and the valve should stop leaking.
If the seat is damaged replacement of the seal is a waste of time as it will just leak again. To stop the valve form leaking now first make sure the valve seat and cock is dry before squeezing the valve body about 1/2 full of RTV. Screw in the cock and tighten the valve until it stops & give it just a tiny bit more....like 5degrees of rotation-ish Wait about 45 minutes for the RTV to cure before refilling the radiator with coolant. This will seal the valve and it shouldn't ever leak again also, don't try to open the valve again.
This type of valves leak because the seal has shrunk over time and no longer presses tightly into the seat, the seat itself is damaged or both.
First step is to clean the seat inside the valve body and inspect it. The seat shouldn't have any cracks and be uniform in shape & have no high or low spots.
If the seat is undamaged replace the cock seal and the valve should stop leaking.
If the seat is damaged replacement of the seal is a waste of time as it will just leak again. To stop the valve form leaking now first make sure the valve seat and cock is dry before squeezing the valve body about 1/2 full of RTV. Screw in the cock and tighten the valve until it stops & give it just a tiny bit more....like 5degrees of rotation-ish Wait about 45 minutes for the RTV to cure before refilling the radiator with coolant. This will seal the valve and it shouldn't ever leak again also, don't try to open the valve again.
-
puttputtinpup
- Regular Member
- Posts: 11671
- Joined: Sat Oct 08, 2005 5:18 am
- Location: Winston Salem, NC
Re: Radiator Drain Plug Leakage
Exactly!isuzu Specialities wrote: ↑Sat Jun 07, 2025 2:44 am When the valve is closed the cock forces a seal up against a seat located inside the valve body.
This type of valves leak because the seal has shrunk over time and no longer presses tightly into the seat, the seat itself is damaged or both.
First step is to clean the seat inside the valve body and inspect it. The seat shouldn't have any cracks and be uniform in shape & have no high or low spots.
If the seat is undamaged replace the cock seal and the valve should stop leaking.
If the seat is damaged replacement of the seal is a waste of time as it will just leak again. To stop the valve form leaking now first make sure the valve seat and cock is dry before squeezing the valve body about 1/2 full of RTV. Screw in the cock and tighten the valve until it stops & give it just a tiny bit more....like 5degrees of rotation-ish Wait about 45 minutes for the RTV to cure before refilling the radiator with coolant. This will seal the valve and it shouldn't ever leak again also, don't try to open the valve again.
