HI everyone, Whats involved in replacing head gaskets on a 351c, temp is reaching the half mark , oil is clear with no signs of water and radiator is bubble free but has a leak in bottom tank , have checked thermostat and its works , i have noticed it has very little water flowing through top tank but seems free of blockages. Could a sluggish water pump be the cause for rising temps and only have steam and clear spits of water coming from exhaust on warm up only and would think this is normal when running LPG. Any ideas where and what else to check at this point.

 

Since radiator is leaking anyway have it repaired and cleaned. Pick up a cheap mechanical gauge and install so you know what temp it's really running. Pull plugs and see if any are super clean indicating water in cyl. Though I'm not familiar with what they look like on LPG, you should see a difference on a bad cylinder. Everything I have spits water on warmup=normal.

 

Get the leak fixed and have the system psi checked. The water pump is not causing this.

 

Radiator restriction is very possible, you can have it flow trested while you have it at the radiator shop getting that leak in the tank fixed. I've had it happen once even on a 50,000 mile 1991 Chevrolet Caprice police car and it had to have a new radiator .... it was just barely broken in and original mixture less than two year old.

A flowcooler water pump plate that riveted to the vanes of my water pump impeller with stainless steel rivets reduced cavitation and improved cooling on my 351M in conjunction with the correct Robert Shaw 333-192 T-stat, runs cooler with that set up than it did when I got it and tried a std 180 Stant T-stat.

The 351M and 400s use a lip or "hat" on the T-stat pill in conjunction with the cast in block restrictor to reduce flow through the bypass more as the T-stat opens, forcing more flow through radiator.
The opening moves the hat closer to the cast in block hole.
The 351C has a pressed in the block restrictor in place that serves the exact same porpose and it uses the exact same Robert Shaw 333-180 or 333-192 T-stat.

289 and 302s have a different restriction designed in the bypass hose, the bypass on the 351C / 351M / 400 is not in a hose.

If the restriction is ignored, if the right diameter T-stat is used based solely on diameter and it lacks that hat or lip, there is no increase in restriction as the T-stat opens and much of the hot coolamnt simply takes the patch of least resistance to the water pump through the open bypass and never sees a radiator and in hot weather the little bit that does see the radiator is moving so slow and is so little that it cannot adequately cool the engine. Steady increasing engine temps result, it will overheat.

Get a real temp gage too.

 

thanks for the replies , i'll start back at radiator shop and work down from there and let ya's know what i find.
cheers