1999 Tarago Temp dropping rapidly when you accelerate fast.....Any ideas????

[st78]

Hi Everyone,
Well I've just replaced the engine in our 1999 TCR10 Taarago. Ended up putting in a lowish km motor out of a 1992 tarago (both 2TZ-FE Engines) Mind you pretty well the only thing that was the same was the block itself. Anyway changed everything needed and got it in running fine (pr#ck of a job!) But now when you put your foot down and give it a good kick in the guts the temp guage drops down dramastically (almost to cold) when you back off it comes back up to normal running temp. If your just driving normally its fine untill you give it a bit up a big hill or put your foot down to overtake etc and same thing temp drops. To the extent its doing this I cant see the engine temp could fluctuate so quick so im thinking its gotta be either the temp sender or guage in dash (although both are the original sendor and cluster off my old motor and car and it never used to do this. Any ideas or suggestions would be greatly appreciated. Thanks in advance

[Dan_k36]

Thermostat replaced?

[st78]

No not yet, Motor has only been in a cpl of days and I wanted to give it a bit of a run and flush with just water (have dumped water a cpl of times) before putting coolant in but have got new thermostat here ready to go in within the next day or so then put the proper coolant in. I was thinking maybe thermostat too but didn't think that would cause rapid drop in temp like its doing according to the guage....Would it?

[Dan_k36]

If its Jamed open only a little it cause those problems, is the top hose the same temp as the bottom when up to temp?
Do u no if it had one in it when u fitted it?

[st78]

Nah, didn't take alot of notice to be honest as I knew I was putting a new one in it anyway (anytime I get a new car, put new motor etc in I always do the thermostat (better to be safe than sorry) there was a bit of corrosive crap in hoses etc and thats why I thought I'd flush it with clean water a few times before doing thermostat and coolant. Took car the motor came out of for a drive to test it all and make sure it was all good but didn't notice it dropping temp but then I only went around the block one night (large country block) as car I got motor out of was a repairable write off and couldn't drive too far. Will do thermostat and coolant in next day or so and hopefully that fixes the problem