IH TD-25B Over heating

If the pump were going bad on that machine, you would either not be running or would have a definate miss. If one of the tips went bad the spray pattern would be off or you would be slobbering all over the place. You are not having that problem right now from the sounds of it.

It still might be a cracked head. I have seen it on the older TD9 series where the head is cracked and it is not showing by bubbles in the raidiator.

When you take it apart, look at the cylinder walls to make sure you are not starting to score.

Also they will run hotter if the precomubustion cup is bad. They get badly pitted over time.

Good luck.

Could your timing gears be worn or be wobbling on one of the shafts just enough to cause it to be out of time as rpm goes up. If your timing were to far off the engine would be really run hard.

You said that after the pump was replaced you started to have problems?

What is she running without the cap? It is a presured system, but the water at the top of the radiator should be w/in a few degrees of that from that measured at the top of the head. 225+ is way too hot, Too hard on too many things unless you were running a synthetic oil which has a thermal breakdown of around 1500 degrees. The rubber that is used to make conventional mult-vis oil starts to break down really fast at that heat and engine pressure.

Other possibilities are exhaust blow by on the valves. Have you checked compression. I would presume the head was a rebuilt/rewelded or was it from salvage but tested good. Was there a full valve job done?

You have rodded the raidiator and flow checked it?

There still exists the possiblity that in the last 6 years it may have finally cracked.

This works only on radiators that can be taken apart and the core worked one.

That is quite a cooling differential between the head and the top of the radiator.

Would be interesting to see what happend without a thermostat. The engine will not come up to temp as fast but should get get there. You should have full water flow ect to the whole system. The bypass should not be into play either.

If they are out of adjustment you can burn a valve over time or ruin the valve seat. You can check valve lash to check on that and the springs are supposed to have a particular setting for pressure when depressed. Most engines is is over 300lbs for valve springs. If it less than that over time deposits will build up there and the valve will not fully close.