volvo 131 running hot

[the toy]

hi 88 volvo 131 /290 outdrive.new impeller flange at lower unit good ,new thermostat.runf hot after running at anything over half idle.after about 20 minutes. run below that its 200 .idle speed 180.want any advice,also anyone now how to clean heat exchanger without removal?thought of cleaning with radiator flush.cking to see if possible restriction.felt raw water housing appears slightly warm sometimes cool others.believe main coolant pump problem when under load.just thought id ask for anyother opions.know norestrictions in exhaust or raw water system.thanks in advance for your help.ernie note only ran 5-10 minutes before replaced rad cap on expansion tank ,prev owner had 7 pd cap on there manual said 15 required.

 

[jerryjerry05]

Re: volvo 131 running hot

I'd check the manifold before I worry about the exchanger.If it's original it's probably bad.The exchanger:you might get lucky by flushing with muratic acid.If that doesn't help removal and back flush and acid wash(the acid can ruin it if not careful).
That system is prone to a lot of problems:manifold,exchanger,waterpump cam,
pump seals,pump wear(soft brass).
The manifold if original,can't really be cleaned.You might clean the outlet but the real damage is inside.Jerry