AQ130C over heating and TachDwell Problems

"I am new to the discussion bo

"I am new to the discussion board, I have been searching for answers to two problems. I just completed a complete engine rebuild of my AQ130C Volvo engine. One problem is that the engine temp runs at 160deg below 1500rpm as soon as I bring the speed up (under load) the temp rises to about 200 + degrees. I have checked the thermostat (ok) the sea water filter is clean and the pump impeller is new. I noticed that the head and block have elongated holes for the water and the head gasket has round holes, could this be my problem (restricting water flow) I removed the exaust manafold and cleaned it, found a lot of scale (I have not lake tested since). Any Ideas? My second problem is setting the dwell. I do not have the manual for this boat. Does the dwell meter connect across the coil (+ and -) or from the coil "-" and to the block. 61 degrees seems to keep the coil on most of the time when the dwell meter is connected from the coil "-" to the block."

"Re: overheating: check the ho

"Re: overheating: check the hose connector in the outdrive (looks like a thermostat housing). Disconnect the hose, and if the connector is corroded, replace it, as it may be perforated and causing the pump to suck air once the boat is on the plane (this is a very common cause of overheating problems in Volvo Penta older outdrives). You can finde the Sierra aftermarket part in the following link:

http://www.marineengine.com/parts/part_details.php?pnum=SIE18-2778&returntopage= 80240788.htm

If you found a lot of scale in your exhaust manifold, I think you should consider taking it to a radiator shop and "boiling" it. That would clear any obstruction it may have.

To test the points dwell angle, connect the + lead of the meter to the (-) of the coil, and connect the (-) of the meter to ground."

Thank you for the quick respon

Thank you for the quick response. I have installed a clear hose on the intake going from the yoke to the sea water filter. I do not see air unless the drive is in a buket of water. I quit using the muffs as they tend to fall off or leak. Is it possible to have a air leak in the out drive below the hose connector? The hose going from the connector to the yoke is good.

"I cannot see the possibility

"I cannot see the possibility of a leak below the hose connector, because there is only a straight tube running to the water intake chamber in the lower unit. However, I suggest you should check that the water intake grids in the lower unit are not clogged due to corrosion or marine growth.

If both the s-hose and hose connector are in good condition, I think that your problem may be caused by a clogged exhaust manifold or choked tubes in the oil cooler. I assume that you boiled the block when you did the engine rebuild or at least ensured that there was no sediment or scale in the cooling passages."

"Thank you for the quick respo

"Thank you for the quick response. I have removed the coupler on the drive and the seal is dried out and has cracks. I cleaned the coupler including around the hose connection. I made a new gasket with a flat piece of rubber and an "O" ring by bonding them together (just to try) This helped and also I no longer see air in the intake line when the drive is in a large bucket of water. The temp still runs around 160 +/- 10 degrees at low rpm. When running at high rpm the temp still rises to 220 degrees and holds. I noticed that if I open the water drain valve on the block (not oil cooler) the engine temp immeadialy drops to below 160. I think this tells me that water is not circulating in the block unless I provide a place for it to go. Question, There is a hole in the water distibution housing over the theromostat. This hole is for bypassing the engine block when the engine is cold. It appears that the thermostat top is suppose to block this hole when the water in the block reaches temp. Is the thermostat supose to close off this hole when the engine reaches temp and the thermostat opens? I am wondering if the thermostat is not sealing against this hole, thus allowing too much fresh water to excape without circulating through the block. Is there supose to be a rubber sealing surface in the hole to provide for a better seal when the thermostat opens?

I have tried three thermostats including the one that was in the engine last year (worked then). They all act the same.

The head and block were both boiled and descaled. I took the exhaust manafold apart and cleanded it, there was alot of scale. It is now clean. I also flipped the impeller over and put it back in. Saturday we went to the lake and now the pipe leading from the pump to the oil cooler pops out at high speed, think the water presure has increased. I replaced (again) the rubber "O" ring on the pipe and reseated it.

Monday I will order a new gasket and coupler."

"Bob, my feeling is that the e

"Bob, my feeling is that the exhaust manifold needs either boiling or replacing. The two places where you normally get a raw water obstruction are the exhaust manifold and the oil cooler; I do not count the block and the head because they have been boiled and descaled. Unfortunately, you cannot reach all the internal parts of the manifold, so the only way to make (reasonably) sure that all the internal scale is gone is boiling it in a specialized place (like a radiator shop). When it comes to the oil cooler, just remove it, open it and rod the tubes to remove any mud or scale that may be there."

"OK! I am unable to get the c

"OK! I am unable to get the cartrage out of the oil cooler. Hoever I cannot see any obstructions in the oil cooler. What is the trick to remove the cartrage without damaging it and what do you recommend to use to get the mud and/or scale from it? I found out that the thermostat was not opening up enough to close off the upper port of the water distributer. I have now ordered a new thermostat and gasket for the hose coupler on the out drive. Should be in later this week. I will remove the exhaust manafold and have it cleaned. I did check all the copper tubes. It would be nice to replace them, the owner before me has bent and deformed them. Are these available? The ones I really need are the one that comes from the exhaust manafold and the one from the water pump to the oil cooler."

I'm not aware that oil coo

I'm not aware that oil coolers have a removeable cartridge. Most are brass and are soldered together.

"That was a quick response. T

"That was a quick response. The cartrage is loose, however hangs up sliding all the way out. The shop manual that I have gives steps for removng the element from the housing and soaking it in Muriatic acid. I can get it about 1/2 way out and then it hangs up. I did not want to force it."

"The Volvo 4-cylinder engines&

"The Volvo 4-cylinder engines' oil coolers have removable end covers, which are bolted to the tube nest and each is sealed with an o-ring. Once you remove the covers, then a rod of the appropriate size can be passed through the tubes to remove mud. You don't need to remove the cartridge unless you see large deposits of scale, in which case you will have to send it to be boiled in a radiator shop.

The copper pipes are probably available through Volvo, but not likely aftermarket."

"I have flushed out the comple

"I have flushed out the complete system, back flushed the water intake from the drive, cleaned and boiled the oil cooler element (which is removable) cleaned and checked the passages in the exhaust manifold. Checked and cleaned the riser tube water discharge port, tested and changed the thermostat and still have overheating problems. I tested the engine compression and found that the compression is 130 to 140 lb between all cylinders. I have noticed that I hear air rushing in the head when I turn the engine over using a ratchet on the crank shaft. I think my valves are leaking. Is it possible that leaky valve seats (head gasket is new) could cause the engine to run hot? This is a newly rebuilt engine."

"Do you know how to perform a

"Do you know how to perform a leakdown test? You may want to either perform one or ask someone else to do it for you. This will tell you where the leaks are coming from: worn cylinder/piston rings, worn intake/exhaust valves, or head gasket. A new head gasket will not help if the head is warped or if some of the sealing surfaces in the block and head are not flat."

I have a compression gauge. I

I have a compression gauge. I know how to use this to do a compression test wet and dry. How do I do a leak down test? Is it possible that a leaky valve could cause high temp? I am at a loss as to the cause of the high temp.

"Bob, check these links regard

"Bob, check these links regarding how to perform a leakdown test and how to make your own tester -I made my own time ago, it is not so difficult-
:

http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm

http://vmaxoutlaw.com/tech/leakdown_tester.htm

You can get more information through Google.

A leaky valve can cause high exhaust temperature, which in turn could cause high coolant temperature. Nevertheless, according to SELOC your engine should have between 170 to 200 PSI compression. Also, you may be reaching a situation where you are putting too much fuel into the engine as you can not burn it efficiently because of lack of compression. This could explain the high water temperature you are experiencing."