'88 Integra Running Slightly Hotter After New Radiator
 

Hello,

A few months back I installed a new radiator in my 1988 Integra. Everything works fine with the exception that the thermostat reading is slightly higher than before. Doesn't read in the critical range just a little hotter. This is confirmed by the spark plugs having a grayish look to them similar to the shop manual photos of hotter running engine.

When replacing the radiator the only thing that caused me problems was removing the engine block plug (couldn't remove and thought that a little old fluid might not hurt) and performing a flush. Is there special equipment for thorough flushing? Should I take it in to have this done or could the problem lie somewhere else?

Any ideas or insights appreciated. Thanks in advance.

Sounds like you might have some air stuck in the block. Not sure on the procedure for the 88, but it usually takes a while to get all the air out of the system. I'm sure someone here can advise you of the proper way.

no special equipment needed to do the flush. i think it just has bubbles in it. I never really opened the bolt on the block. I dont think its absolutely needed.

After adding fluid, you should start up the cold engine and leave the radiator cap off. Wait for the engine to get hot (about 15-20 min should be good) so that the thermostat opens up. You should see bubbles come up. Add more fluid/water as needed, then cap it off.

some hondas have a bleeder bolt at the end of the top radiator tube. I never use it. In fact i dont really know the proper way to use it. i believe you can bleed bubbles there too. but be carefull, the water is boiling hot, dont get splashed.

also note: DONT take off the cap on a hot engine. wait for the engine to cool, take the cap off, THEN start the engine, and wait for bubbles to come out.

Another problem could be that the thermostat needs to be changed. Check you manual for suggested change intervals.

I usually change my thermostat 40,000 miles or every 2years for the amount of miles i drive.

did u fill up the block with coolant ? i know it seems basic, but a lot of people skip it when doing a drain/refill.

i've seen a lot of people fill up the radiator by pouring it in the top of the radiator...and thats it. You have to also fill the block by pouring it in via the upper radiator hose.

if you did that, maybe something corroded?

Like I said, it's been about six months but my recollection now is that I couldn't remove the lower engine block plug. I removed the bleeder bolt on the top of the engine block (to remove air bubbles) and fluid started flowing out so I immediately screwed the bolt back in and filled the radiator with fluid through the top of the radiator. Reviewing the Haynes Repair Manual instructions I was following, it says to run the engine with the cap off until upper hose is warm and then add more fluid, if necessary. The instructions don't say anything about filling the block through the upper radiator hose. So, does it sound like I inadvertently let some air in somehow? Should I remove the upper radiator hose and fill it with antifreeze? If I could catch a $39.99 sale on flushing the radiator I'd go for it but without a sale I think the rate is $70-100 - a little steep if the solution is simply adding fluid to the upper radiator hose. Thanks again. You guys are the best!

if fluid started flowing out then it should mean the block actually has fluid. so you're good there.

would u happen to have a coolant system pressure test kit?

if theres a leak in the cooling system and it cant hold its 1.1 BAR internal (~15psi) pressure then the boiling point of the coolant isnt as high as it should be. places to look for a leak are radiator caps, overflow nipples, freeze plugs, heater lines, etc.

Thanks, Spec R. Will check pressure ASAP.

Problem Likely Solved
 

Thanks for all of the helpful replies.

Although probably need more time to confirm, initial impression is that the radiator cap was the weak link. Following Spec R's suggestion of looking for weak pressure in coolant system I replaced the radiator cap and temp gauge seems to be back at the same spot it has spent the past 21 years. Gotta love those simple, inexpensive solutions!

Thanks,

My 96 GSR has 297,000 miles and I have changed the radiator twice and it has ran warmer since I changed it the first time at 135,000 miles. The new radiator is suppose to be heavier than the OEM but it runs warmer. I noticed that it has bigger tubes running through it but since the tubes are bigger, there are less tubes than the OEM. I think the tubes are called cores but I dont remember... I't try you technique.

if the thermostat's never been replaced replace it, new radiator cap also helps, pressure its what keeps the engine cool.

Questions on Thermostat Replacement Procedure and Brand
 

Joe, been thinking about replacing the thermostat but have been leaning toward the "if it ain't broke, don't fix it" school of thought. As both you and Alfred testify to the importance of this item I'm reconsidering it. Also, my conclusion that the radiator cap was the fix may have been mistaken.

Must admit that I've been influenced by the Haynes Integra and Legend Repair Manual which combines the instructions on thermostat replacement for both models. It states that one must drain the radiator fluid before replacing thermostat but then goes on to describe the part's location on the Legend as next to the lower radiator hose and the one on the Integra as next to the distributor. To get to the point, draining the rad fluid when i changed the radiator was a messy affair (without a lift) and this has influenced my desire to tackle this project.

Can anyone comment as to whether it is necessary to drain the rad fluid when replacing the thermostat on this model? I believe Autozone rep said it's not necessary and its position on top of the engine block (my recollection?) suggests that he may be right in his claim that this is a simple procedure on this model.

Autozone rep also suggested the Failsafe 170 degree (OEM spec) thermostat over the OEM part because it is designed so that in the event of failure it will always fail in the open position. Have always preferred OEM items but if there has been a design improvement since the car was made then perhaps this is an exception. Any suggestions on Failsafe thermostats (or any other brand) versus OEM? Based on the MotoRad's certification of ISO 9001 and the automotive standard of QS 9000 I'm inclined to believe that this is an exception to the OEM rule.

Here's a couple of links describing the Failsafe part http://www.autozone.com/autozone/cat...dName=Failsafe
http://www.motoradusa.com/products/f...rmo/index.html

The thermostat is always one of those cheap insurance items. I've never looked much into a fail-safe one, I've always just used OEM.

As to draining, I'm fairly sure you should drain the radiator, but just the radiator. The t-stat housing should be high enough that you don't need to drain the block. Does you new rad not have a drain petcock on it?

maybe water and coolant mixture is not correct.

Lynxs, was persuaded by your "cheap insurance" argument. Purchased a Motorad Failsafe 170 (OEM rec'd temp) and will try to get it installed soon.

Cruz, I took care to get the proper water/coolant mixture. However, as stated earlier, I only changed the fluid in the radiator as I could not loosen the engine drain bolt. Perhaps there was a difference in the new coolant mixture I added when I changed the radiator and the fluid in the engine block.

After replacing the t-stat will hopefully be able to post a successful conclusion to this matter.

Thanks all!