My son just put another rotary / 13B I believe in his 7 and it wont stop getting hot. Can't figure out why. Done everything I know. I personally dont know squat about rotary engines. I kind of had the same problem with my dodge truck and it turned out to be the radiator was stopped up and even though water would flow through it it was still the problem. could this be the prob. or is there something were missing? any info would be appreciated. Grumpy

 

Have him check the waterpump for starters.

If the old engine wasn't overheating, and the new engine is-- you can rule out the radiator.

If the old engine was blown, it could have gotten overheated in the first place, which could have been initiated by a clogged radiator.

Either way it probably needs to be cleaned.

Is the replacement motor known in good health? If its just some core block and its condition is unknown/not rebuilt its all a guess. Hopefuly your son knows the risk of installing a used unknown condition motor.

Anyhow, start with the basics. Coolant ,Radiator, water pump, ect. I forgot to mention the clutch fan. When its got a fail-safe, so when it does fail-- it will lockup fulltme. Check to make sure the waterpump pulley isn't siezed or anything like that.

Make sure the car still has the stock clutch fan. If it was modified and the engine is using an electrican fan, it MUST have a proper ducting forcing air through the radiator, or eslse air goes around it. Also, reinstall the underbelly pan if you haven't already, its crucial to proper cooling (though this is debateable-- some people say its trivial, in order to fix your cooling problem, fix all probably causes one by one, starting with the least expensive...)

A little more info would be helpful. Does it always overheat or just sometimes?