I have a B20B8 in an 89 Integra DA9 model.

It originally had a B18??? non vtec in it.

A few years ago I fitted a B20B from 2000 model CRV it had no knock sensor and was I think 8.8: CR model. We retained the original 89 model DA9 ECU, dissy, manifilds, injectors and all sensors, ancillaries etc. All went fine for two years until it broke a timing belt. Fixed that including rebuilt head, but it over heated on refitting head. Original radiator was real second hand so replaced it, all OK after that except it started using a bit of oil.

2 months later the belt jumps a tooth and bends valves again, so as it now used oil I replaced it with a 2002 CRV B20B8 with knock sensor and I think 9.6:1 CR.

Before fitting the engine, I replaced all the belts, oil seals, timing belt tensioner and water pump with new items.

Would not start, on checking timing, found the camshaft hard to turn. Further investigation revealed a tight, almost seized distributor. Replaced distributor and started instantly and ran fine, but on an extended test drive it overheated, more at low speed than high speed. The faulty dissy was good news as it explained the belt problems and was fixed.

Checks found the fans only came on when the AC was on, so another test drive with AC left on. Still overheated, but more so at medium to high speed and high load.

I had spare temperature sensors and a spare thermostat.

Tested thermostat, changed all sensors. Fan still only works with AC on, engine still overheats.

The only thing not changed was the water pump, but it was brand new. I will change it for the best of the second hand ones tomorrow.

I rechecked the cam timing. Definitely OK.

It does not loose coolant or pressurise beyond the normal for the temperature.

My timing light blew a bulb so I set ignition in the middle. Ran sweet, advanced until it became harsh under acceleration then knocked it back a tad until it was sweet again.

I did notice the engine I just put in has some signs of corrosion on the aluminium surface inside the old water pump and thermostat housing. It did seem enough to have a small influence on heat transfer, but not so much as to really restrict flow unless it formed in a very narrow passage..

If it is not a defective brand new water pump or a foreign object restricting flow in some unseen passage, I cannot think what else there is to check.

How would one check for restriction inside the water jackets without dissasembling the engine.

 

Fixed fans it was the thermo switch in the thermostat housing.

Pulled water pump and it appears perfect.

Back flushed radiator, pipe from pump to thermostat, head and block. no apparent restrictions anywhere.

 

Still overheats under load

 

Are you using stock DA rad, if so, replace with bigger rad, dual or triple core.

Make absolutely sure rad and condenser fans are running in the proper direction, seen that problem more then once on engine swaps. 94

 

Id guess your timing is a tooth off..

 

FCM

I replaced the radiator about 2 months ago with the previous B20B engine and it ran on the lower side of normal which I think was right on the thermostat opening temp. It sat there rock steady up a mountain at full load, any speed.

The first B20B ran on the very old OEM radiator for 2 years no problem until the OEM radiator gave up from old age rather than insufficient capacity. I never counted the cores, but the new one is noticably thicker and is the full thickness of the header tank which appears to be about 2" without actually measuring it. The old one by sight was noticably thinner than the header tank. Both header tanks appeared identical and fitted the OEM brackets perfectly, but without actually measuring.

First thing I checked was the draft off the fans. They both run the correct way with a strong draft. I have checked this about 3 times now.

The only difference is the B20B with 8.8:1 CR was replaced with a B20B with 9.6:1 CR. I really can't believe that 0.8 change to compression is making that much difference.

Also, bottom hose is cool but top hose is hot. It does not pump water out the overflow until it boils and I stop before that happens. It has boiled at idle after I stoped and I shut it down. The radiator was under normal pressure and lost only a small amount of water to the overflow. It refilled as normal from the overflow on cooling.

I have again tested both thermostats in a pot of water on the stove. Both opened a bit before the water boiled and both where wide open before it was fully boiling.

I am starting to wonder if the pump impellor on a brand new pump is slipping only when hot. It feels tight by hand when tested cold obviously out of the car. I know, really stupid but what else. I also wondered if I left the plastic protective cover on the impellor when I fitted the pump. No sigh of the bright blue plastic or restriction on dissasembly. Even if I forgot to remove it, I am sure it would have interfered noticably when fitting. It was fitted with the engine out of the car where acces was easy and things easy to see.

No blue plastic flushed out on back flushing. There was no apparent restriction to water flow on back flushing.

I will look closer at the new pump side by side to the old pump and refit the old pump today.

I will pressure test the system today.

I will reluctantly test it with no thermostat today.

I will take even more care to ensure all air bubbles have purged and will remove the heater hoses to fill the heater seperately so I an be sure of no air bubbles, but I slowly filled it, squeesed the high spott on the bottom hose a number of times to pump out any air bubbles, left it 10 min, topped up, repeated until no more water was required, ran at idle with the cap off until the top hose was hot and no more air was escaping. Repeated until it was hot enough to be nearly boiling with the cap off and fans not running. Repeated with fans running several times.

Also the crank pully bolt tightened up so much that a 3/4" drive electric rattle gun would not budge it. I applie heat till first signs of red, still no go, more heat till bright red, still no go, alowed it to cool of, still no go, then even brighter red with some signs of melting on the bolt, stll no go then the whole head of the bolt glowing bright red, front cover and brand new timing belt on fire, finally it came off. Now I need another new belt, front cover and I expect front seal. This engine hates me.

psycho
Timeing was not a tooth off.
Marks lined up perfect. They were checked and double cheked by different people on at least 3 seperate occasions.
It started first go (once a good dissy was in) and ran fine and made at least as much power as the previous motor. It pulled strong from 500 rpm in top gear and ran to the rev limiter in first and second and was going real strong in third before I ran out of road and become to concerned about being taken away in handcuffs if I was caught going any faster (like probably 140 kph in an 80 limit).

 

Oh, by the way guys, thanks for your replys. This is really starting to make me depressed and I desperately need the car to attend to other urgent business.

 

Flushed and reverse flushed again through all points in all directions. All flow everywhere including through heater was clear and free. Not a trace of foreign body or debris.

Water pump definitely OK fits old block OK

Inspection of old block and head proves all water passages big enough or plentiful enough to not be blocked by any possible debris.

I did notice several 1/4" water hoses to the inlet manifold with one going to a 3 way valve just under the throttle body and abother going to a valve on the back of the manifold. I need to determine the functions of each (they appear to be heaters or ice prevention for idle control at first glance). They may also function as a thermostat bypass to allow enough flow to heat the thermostat.

I will search for diagrams or another car I can check out.

I will report back

 

So have you checked the timing since its overheated or no? Its possible it skipped a tooth. Also, dont just look at the cam gears, make sure that not only the cam gears line up, but also that they are lined up when 1 is at TDC. That is what happend with my setup. Cam gears were right, but the crank was off a tooth, which caused it to over heat even at 65mph on the highway on a 70 degree day. Im not implying you dont know what your doing, you just didnt mention you checked the crank postion, just wanted to clarify.

 

I checked the cam timing at TDC. I have done a lot of cam timing and I know it is right.

The more I look, the more it seems that the thermostat won't open unless you have enough bypass occuring to supply hot water to the thermostat heat sensitive element. The symptoms exactly match stuck thermostat which is why that was the first thing I changed. What stumped me was that replacing the thermostat with one tested and proved OK on a stove did not fix it. I should have tested it with no thermostat next. Pulling the water pump before that was a mistake.

 

A cool lower hose and hot upper hose would indicate no coolant flow, either water pump, blocked passage or thermostat not opening, I would pull thermostat and run without one, engine temp should run lower then normal.

Your right, pulling thermostat first would have been the easiest, even if just to eliminate it as the problem.

It is a good bet you have a dual core rad and it should work just fine to cool the engine. 94

 

It's fixed.

It was the cabin heater and thermostat bypass hoses on the wrong way round.