My 04 Deville has a Promar engine in it for about 6 months now, have had no problems with it. the engine was completely rebuilt from the bottom up, not just the head bolts, it is just like a new motor, and it came with a 3 year unlimited mileage warranty. Keep in mind it is only a long block, all the accessories, sensors, coils, plugs etc will need to be swapped over. Any full service garage should be able to do the swap.My 20 yr Cadillac mechanic has said I have a blown head gasket - yet I continue to drive the Northstar without any performance problems -only 82k on motor. I only drive short distances in case the temp gauge goes beyond center - oddly enough driving short distances -the temp gauge slowly advances toward HOT (one notch away) and will return to center mark - to me that seems like a faulty ECT sensor - how can the sensor be reading "over heating" and then return to the center - true overheating should bury the gauge to the right. I have researched all the solutions for fixing the Northstar blown head gasket and the Northstar Performance stud kits seem like a great solution BUT - it does not solve a reseal of the bottom end of a 20 year old Northstar. More labor - it looks like a BETTER solution would be a new remanufactured Northstar - Promar Engines seem to have solved the Northstar head bolt/blown head gasket problem. Their website says" we use proper block strengthening techniques to ensure no more blown head gaskets" How do they do that??
I would hope we could encourage Submarine 409 to call and confirm Promar really has a good solution. Their engine is $3399 plus local installation( probably about $2k) for a total of about $6k - a lot of Cadillac Eldorado owners would be willing to invest the $ - if they thought their problem would be solved.
Cadillac forum is a godsent for the owner's looking for help - evaluating Promar's Northstar would really help all of us - with blown head gasket problems.
I hope Submarine 409 will make an effort to help us all - as he always has in the past.